diff options
Diffstat (limited to 'Documentation')
25 files changed, 197 insertions, 166 deletions
diff --git a/Documentation/ABI/testing/sysfs-devices-system-cpu b/Documentation/ABI/testing/sysfs-devices-system-cpu index 99983e67c13c..da95513571ea 100644 --- a/Documentation/ABI/testing/sysfs-devices-system-cpu +++ b/Documentation/ABI/testing/sysfs-devices-system-cpu @@ -162,7 +162,7 @@ Description: Discover CPUs in the same CPU frequency coordination domain What: /sys/devices/system/cpu/cpu*/cache/index3/cache_disable_{0,1} Date: August 2008 KernelVersion: 2.6.27 -Contact: discuss@x86-64.org +Contact: Linux kernel mailing list <linux-kernel@vger.kernel.org> Description: Disable L3 cache indices These files exist in every CPU's cache/index3 directory. Each diff --git a/Documentation/RCU/arrayRCU.txt b/Documentation/RCU/arrayRCU.txt index 453ebe6953ee..f05a9afb2c39 100644 --- a/Documentation/RCU/arrayRCU.txt +++ b/Documentation/RCU/arrayRCU.txt @@ -10,7 +10,19 @@ also be used to protect arrays. Three situations are as follows: 3. Resizeable Arrays -Each of these situations are discussed below. +Each of these three situations involves an RCU-protected pointer to an +array that is separately indexed. It might be tempting to consider use +of RCU to instead protect the index into an array, however, this use +case is -not- supported. The problem with RCU-protected indexes into +arrays is that compilers can play way too many optimization games with +integers, which means that the rules governing handling of these indexes +are far more trouble than they are worth. If RCU-protected indexes into +arrays prove to be particularly valuable (which they have not thus far), +explicit cooperation from the compiler will be required to permit them +to be safely used. + +That aside, each of the three RCU-protected pointer situations are +described in the following sections. Situation 1: Hash Tables @@ -36,9 +48,9 @@ Quick Quiz: Why is it so important that updates be rare when Situation 3: Resizeable Arrays Use of RCU for resizeable arrays is demonstrated by the grow_ary() -function used by the System V IPC code. The array is used to map from -semaphore, message-queue, and shared-memory IDs to the data structure -that represents the corresponding IPC construct. The grow_ary() +function formerly used by the System V IPC code. The array is used +to map from semaphore, message-queue, and shared-memory IDs to the data +structure that represents the corresponding IPC construct. The grow_ary() function does not acquire any locks; instead its caller must hold the ids->sem semaphore. diff --git a/Documentation/RCU/lockdep.txt b/Documentation/RCU/lockdep.txt index cd83d2348fef..da51d3068850 100644 --- a/Documentation/RCU/lockdep.txt +++ b/Documentation/RCU/lockdep.txt @@ -47,11 +47,6 @@ checking of rcu_dereference() primitives: Use explicit check expression "c" along with srcu_read_lock_held()(). This is useful in code that is invoked by both SRCU readers and updaters. - rcu_dereference_index_check(p, c): - Use explicit check expression "c", but the caller - must supply one of the rcu_read_lock_held() functions. - This is useful in code that uses RCU-protected arrays - that is invoked by both RCU readers and updaters. rcu_dereference_raw(p): Don't check. (Use sparingly, if at all.) rcu_dereference_protected(p, c): @@ -64,11 +59,6 @@ checking of rcu_dereference() primitives: but retain the compiler constraints that prevent duplicating or coalescsing. This is useful when when testing the value of the pointer itself, for example, against NULL. - rcu_access_index(idx): - Return the value of the index and omit all barriers, but - retain the compiler constraints that prevent duplicating - or coalescsing. This is useful when when testing the - value of the index itself, for example, against -1. The rcu_dereference_check() check expression can be any boolean expression, but would normally include a lockdep expression. However, diff --git a/Documentation/RCU/rcu_dereference.txt b/Documentation/RCU/rcu_dereference.txt index ceb05da5a5ac..1e6c0da994f5 100644 --- a/Documentation/RCU/rcu_dereference.txt +++ b/Documentation/RCU/rcu_dereference.txt @@ -25,17 +25,6 @@ o You must use one of the rcu_dereference() family of primitives for an example where the compiler can in fact deduce the exact value of the pointer, and thus cause misordering. -o Do not use single-element RCU-protected arrays. The compiler - is within its right to assume that the value of an index into - such an array must necessarily evaluate to zero. The compiler - could then substitute the constant zero for the computation, so - that the array index no longer depended on the value returned - by rcu_dereference(). If the array index no longer depends - on rcu_dereference(), then both the compiler and the CPU - are within their rights to order the array access before the - rcu_dereference(), which can cause the array access to return - garbage. - o Avoid cancellation when using the "+" and "-" infix arithmetic operators. For example, for a given variable "x", avoid "(x-x)". There are similar arithmetic pitfalls from other @@ -76,14 +65,15 @@ o Do not use the results from the boolean "&&" and "||" when dereferencing. For example, the following (rather improbable) code is buggy: - int a[2]; - int index; - int force_zero_index = 1; + int *p; + int *q; ... - r1 = rcu_dereference(i1) - r2 = a[r1 && force_zero_index]; /* BUGGY!!! */ + p = rcu_dereference(gp) + q = &global_q; + q += p != &oom_p1 && p != &oom_p2; + r1 = *q; /* BUGGY!!! */ The reason this is buggy is that "&&" and "||" are often compiled using branches. While weak-memory machines such as ARM or PowerPC @@ -94,14 +84,15 @@ o Do not use the results from relational operators ("==", "!=", ">", ">=", "<", or "<=") when dereferencing. For example, the following (quite strange) code is buggy: - int a[2]; - int index; - int flip_index = 0; + int *p; + int *q; ... - r1 = rcu_dereference(i1) - r2 = a[r1 != flip_index]; /* BUGGY!!! */ + p = rcu_dereference(gp) + q = &global_q; + q += p > &oom_p; + r1 = *q; /* BUGGY!!! */ As before, the reason this is buggy is that relational operators are often compiled using branches. And as before, although @@ -193,6 +184,11 @@ o Be very careful about comparing pointers obtained from pointer. Note that the volatile cast in rcu_dereference() will normally prevent the compiler from knowing too much. + However, please note that if the compiler knows that the + pointer takes on only one of two values, a not-equal + comparison will provide exactly the information that the + compiler needs to deduce the value of the pointer. + o Disable any value-speculation optimizations that your compiler might provide, especially if you are making use of feedback-based optimizations that take data collected from prior runs. Such diff --git a/Documentation/RCU/whatisRCU.txt b/Documentation/RCU/whatisRCU.txt index 88dfce182f66..5746b0c77f3e 100644 --- a/Documentation/RCU/whatisRCU.txt +++ b/Documentation/RCU/whatisRCU.txt @@ -256,7 +256,9 @@ rcu_dereference() If you are going to be fetching multiple fields from the RCU-protected structure, using the local variable is of course preferred. Repeated rcu_dereference() calls look - ugly and incur unnecessary overhead on Alpha CPUs. + ugly, do not guarantee that the same pointer will be returned + if an update happened while in the critical section, and incur + unnecessary overhead on Alpha CPUs. Note that the value returned by rcu_dereference() is valid only within the enclosing RCU read-side critical section. @@ -879,9 +881,7 @@ SRCU: Initialization/cleanup All: lockdep-checked RCU-protected pointer access - rcu_access_index rcu_access_pointer - rcu_dereference_index_check rcu_dereference_raw rcu_lockdep_assert rcu_sleep_check diff --git a/Documentation/devicetree/bindings/arm/omap/l3-noc.txt b/Documentation/devicetree/bindings/arm/omap/l3-noc.txt index 974624ea68f6..161448da959d 100644 --- a/Documentation/devicetree/bindings/arm/omap/l3-noc.txt +++ b/Documentation/devicetree/bindings/arm/omap/l3-noc.txt @@ -6,6 +6,7 @@ provided by Arteris. Required properties: - compatible : Should be "ti,omap3-l3-smx" for OMAP3 family Should be "ti,omap4-l3-noc" for OMAP4 family + Should be "ti,omap5-l3-noc" for OMAP5 family Should be "ti,dra7-l3-noc" for DRA7 family Should be "ti,am4372-l3-noc" for AM43 family - reg: Contains L3 register address range for each noc domain. diff --git a/Documentation/devicetree/bindings/clock/at91-clock.txt b/Documentation/devicetree/bindings/clock/at91-clock.txt index 7a4d4926f44e..5ba6450693b9 100644 --- a/Documentation/devicetree/bindings/clock/at91-clock.txt +++ b/Documentation/devicetree/bindings/clock/at91-clock.txt @@ -248,7 +248,7 @@ Required properties for peripheral clocks: - #address-cells : shall be 1 (reg is used to encode clk id). - clocks : shall be the master clock phandle. e.g. clocks = <&mck>; -- name: device tree node describing a specific system clock. +- name: device tree node describing a specific peripheral clock. * #clock-cells : from common clock binding; shall be set to 0. * reg: peripheral id. See Atmel's datasheets to get a full list of peripheral ids. diff --git a/Documentation/devicetree/bindings/clock/silabs,si5351.txt b/Documentation/devicetree/bindings/clock/silabs,si5351.txt index c40711e8e8f7..28b28309f535 100644 --- a/Documentation/devicetree/bindings/clock/silabs,si5351.txt +++ b/Documentation/devicetree/bindings/clock/silabs,si5351.txt @@ -17,7 +17,8 @@ Required properties: - #clock-cells: from common clock binding; shall be set to 1. - clocks: from common clock binding; list of parent clock handles, shall be xtal reference clock or xtal and clkin for - si5351c only. + si5351c only. Corresponding clock input names are "xtal" and + "clkin" respectively. - #address-cells: shall be set to 1. - #size-cells: shall be set to 0. @@ -71,6 +72,7 @@ i2c-master-node { /* connect xtal input to 25MHz reference */ clocks = <&ref25>; + clock-names = "xtal"; /* connect xtal input as source of pll0 and pll1 */ silabs,pll-source = <0 0>, <1 0>; diff --git a/Documentation/devicetree/bindings/dma/fsl-mxs-dma.txt b/Documentation/devicetree/bindings/dma/fsl-mxs-dma.txt index a4873e5e3e36..e30e184f50c7 100644 --- a/Documentation/devicetree/bindings/dma/fsl-mxs-dma.txt +++ b/Documentation/devicetree/bindings/dma/fsl-mxs-dma.txt @@ -38,7 +38,7 @@ dma_apbx: dma-apbx@80024000 { 80 81 68 69 70 71 72 73 74 75 76 77>; - interrupt-names = "auart4-rx", "aurat4-tx", "spdif-tx", "empty", + interrupt-names = "auart4-rx", "auart4-tx", "spdif-tx", "empty", "saif0", "saif1", "i2c0", "i2c1", "auart0-rx", "auart0-tx", "auart1-rx", "auart1-tx", "auart2-rx", "auart2-tx", "auart3-rx", "auart3-tx"; diff --git a/Documentation/devicetree/bindings/input/touchscreen/tsc2005.txt b/Documentation/devicetree/bindings/input/touchscreen/tsc2005.txt index 4b641c7bf1c2..09089a6d69ed 100644 --- a/Documentation/devicetree/bindings/input/touchscreen/tsc2005.txt +++ b/Documentation/devicetree/bindings/input/touchscreen/tsc2005.txt @@ -32,8 +32,8 @@ Example: touchscreen-fuzz-x = <4>; touchscreen-fuzz-y = <7>; touchscreen-fuzz-pressure = <2>; - touchscreen-max-x = <4096>; - touchscreen-max-y = <4096>; + touchscreen-size-x = <4096>; + touchscreen-size-y = <4096>; touchscreen-max-pressure = <2048>; ti,x-plate-ohms = <280>; diff --git a/Documentation/devicetree/bindings/mtd/m25p80.txt b/Documentation/devicetree/bindings/mtd/jedec,spi-nor.txt index f20b111b502a..2bee68103b01 100644 --- a/Documentation/devicetree/bindings/mtd/m25p80.txt +++ b/Documentation/devicetree/bindings/mtd/jedec,spi-nor.txt @@ -8,8 +8,8 @@ Required properties: is not Linux-only, but in case of Linux, see the "m25p_ids" table in drivers/mtd/devices/m25p80.c for the list of supported chips. - Must also include "nor-jedec" for any SPI NOR flash that can be - identified by the JEDEC READ ID opcode (0x9F). + Must also include "jedec,spi-nor" for any SPI NOR flash that can + be identified by the JEDEC READ ID opcode (0x9F). - reg : Chip-Select number - spi-max-frequency : Maximum frequency of the SPI bus the chip can operate at @@ -25,7 +25,7 @@ Example: flash: m25p80@0 { #address-cells = <1>; #size-cells = <1>; - compatible = "spansion,m25p80", "nor-jedec"; + compatible = "spansion,m25p80", "jedec,spi-nor"; reg = <0>; spi-max-frequency = <40000000>; m25p,fast-read; diff --git a/Documentation/devicetree/bindings/net/cdns-emac.txt b/Documentation/devicetree/bindings/net/cdns-emac.txt index abd67c13d344..4451ee973223 100644 --- a/Documentation/devicetree/bindings/net/cdns-emac.txt +++ b/Documentation/devicetree/bindings/net/cdns-emac.txt @@ -3,7 +3,8 @@ Required properties: - compatible: Should be "cdns,[<chip>-]{emac}" Use "cdns,at91rm9200-emac" Atmel at91rm9200 SoC. - or the generic form: "cdns,emac". + Use "cdns,zynq-gem" Xilinx Zynq-7xxx SoC. + Or the generic form: "cdns,emac". - reg: Address and length of the register set for the device - interrupts: Should contain macb interrupt - phy-mode: see ethernet.txt file in the same directory. diff --git a/Documentation/devicetree/bindings/usb/renesas_usbhs.txt b/Documentation/devicetree/bindings/usb/renesas_usbhs.txt index dc2a18f0b3a1..ddbe304beb21 100644 --- a/Documentation/devicetree/bindings/usb/renesas_usbhs.txt +++ b/Documentation/devicetree/bindings/usb/renesas_usbhs.txt @@ -15,10 +15,8 @@ Optional properties: - phys: phandle + phy specifier pair - phy-names: must be "usb" - dmas: Must contain a list of references to DMA specifiers. - - dma-names : Must contain a list of DMA names: - - tx0 ... tx<n> - - rx0 ... rx<n> - - This <n> means DnFIFO in USBHS module. + - dma-names : named "ch%d", where %d is the channel number ranging from zero + to the number of channels (DnFIFOs) minus one. Example: usbhs: usb@e6590000 { diff --git a/Documentation/filesystems/Locking b/Documentation/filesystems/Locking index 0a926e2ba3ab..6a34a0f4d37c 100644 --- a/Documentation/filesystems/Locking +++ b/Documentation/filesystems/Locking @@ -50,8 +50,8 @@ prototypes: int (*rename2) (struct inode *, struct dentry *, struct inode *, struct dentry *, unsigned int); int (*readlink) (struct dentry *, char __user *,int); - void * (*follow_link) (struct dentry *, struct nameidata *); - void (*put_link) (struct dentry *, struct nameidata *, void *); + const char *(*follow_link) (struct dentry *, void **); + void (*put_link) (struct inode *, void *); void (*truncate) (struct inode *); int (*permission) (struct inode *, int, unsigned int); int (*get_acl)(struct inode *, int); diff --git a/Documentation/filesystems/automount-support.txt b/Documentation/filesystems/automount-support.txt index 7cac200e2a85..7eb762eb3136 100644 --- a/Documentation/filesystems/automount-support.txt +++ b/Documentation/filesystems/automount-support.txt @@ -1,41 +1,15 @@ -Support is available for filesystems that wish to do automounting support (such -as kAFS which can be found in fs/afs/). This facility includes allowing -in-kernel mounts to be performed and mountpoint degradation to be -requested. The latter can also be requested by userspace. +Support is available for filesystems that wish to do automounting +support (such as kAFS which can be found in fs/afs/ and NFS in +fs/nfs/). This facility includes allowing in-kernel mounts to be +performed and mountpoint degradation to be requested. The latter can +also be requested by userspace. ====================== IN-KERNEL AUTOMOUNTING ====================== -A filesystem can now mount another filesystem on one of its directories by the -following procedure: - - (1) Give the directory a follow_link() operation. - - When the directory is accessed, the follow_link op will be called, and - it will be provided with the location of the mountpoint in the nameidata - structure (vfsmount and dentry). - - (2) Have the follow_link() op do the following steps: - - (a) Call vfs_kern_mount() to call the appropriate filesystem to set up a - superblock and gain a vfsmount structure representing it. - - (b) Copy the nameidata provided as an argument and substitute the dentry - argument into it the copy. - - (c) Call do_add_mount() to install the new vfsmount into the namespace's - mountpoint tree, thus making it accessible to userspace. Use the - nameidata set up in (b) as the destination. - - If the mountpoint will be automatically expired, then do_add_mount() - should also be given the location of an expiration list (see further - down). - - (d) Release the path in the nameidata argument and substitute in the new - vfsmount and its root dentry. The ref counts on these will need - incrementing. +See section "Mount Traps" of Documentation/filesystems/autofs4.txt Then from userspace, you can just do something like: @@ -61,17 +35,18 @@ AUTOMATIC MOUNTPOINT EXPIRY =========================== Automatic expiration of mountpoints is easy, provided you've mounted the -mountpoint to be expired in the automounting procedure outlined above. +mountpoint to be expired in the automounting procedure outlined separately. To do expiration, you need to follow these steps: - (3) Create at least one list off which the vfsmounts to be expired can be - hung. Access to this list will be governed by the vfsmount_lock. + (1) Create at least one list off which the vfsmounts to be expired can be + hung. - (4) In step (2c) above, the call to do_add_mount() should be provided with a - pointer to this list. It will hang the vfsmount off of it if it succeeds. + (2) When a new mountpoint is created in the ->d_automount method, add + the mnt to the list using mnt_set_expiry() + mnt_set_expiry(newmnt, &afs_vfsmounts); - (5) When you want mountpoints to be expired, call mark_mounts_for_expiry() + (3) When you want mountpoints to be expired, call mark_mounts_for_expiry() with a pointer to this list. This will process the list, marking every vfsmount thereon for potential expiry on the next call. diff --git a/Documentation/filesystems/porting b/Documentation/filesystems/porting index e69274de8d0c..3eae250254d5 100644 --- a/Documentation/filesystems/porting +++ b/Documentation/filesystems/porting @@ -483,3 +483,20 @@ in your dentry operations instead. -- [mandatory] ->aio_read/->aio_write are gone. Use ->read_iter/->write_iter. +--- +[recommended] + for embedded ("fast") symlinks just set inode->i_link to wherever the + symlink body is and use simple_follow_link() as ->follow_link(). +-- +[mandatory] + calling conventions for ->follow_link() have changed. Instead of returning + cookie and using nd_set_link() to store the body to traverse, we return + the body to traverse and store the cookie using explicit void ** argument. + nameidata isn't passed at all - nd_jump_link() doesn't need it and + nd_[gs]et_link() is gone. +-- +[mandatory] + calling conventions for ->put_link() have changed. It gets inode instead of + dentry, it does not get nameidata at all and it gets called only when cookie + is non-NULL. Note that link body isn't available anymore, so if you need it, + store it as cookie. diff --git a/Documentation/filesystems/vfs.txt b/Documentation/filesystems/vfs.txt index 5d833b32bbcd..b403b29ef710 100644 --- a/Documentation/filesystems/vfs.txt +++ b/Documentation/filesystems/vfs.txt @@ -350,8 +350,8 @@ struct inode_operations { int (*rename2) (struct inode *, struct dentry *, struct inode *, struct dentry *, unsigned int); int (*readlink) (struct dentry *, char __user *,int); - void * (*follow_link) (struct dentry *, struct nameidata *); - void (*put_link) (struct dentry *, struct nameidata *, void *); + const char *(*follow_link) (struct dentry *, void **); + void (*put_link) (struct inode *, void *); int (*permission) (struct inode *, int); int (*get_acl)(struct inode *, int); int (*setattr) (struct dentry *, struct iattr *); @@ -436,16 +436,18 @@ otherwise noted. follow_link: called by the VFS to follow a symbolic link to the inode it points to. Only required if you want to support - symbolic links. This method returns a void pointer cookie - that is passed to put_link(). + symbolic links. This method returns the symlink body + to traverse (and possibly resets the current position with + nd_jump_link()). If the body won't go away until the inode + is gone, nothing else is needed; if it needs to be otherwise + pinned, the data needed to release whatever we'd grabbed + is to be stored in void * variable passed by address to + follow_link() instance. put_link: called by the VFS to release resources allocated by - follow_link(). The cookie returned by follow_link() is passed - to this method as the last parameter. It is used by - filesystems such as NFS where page cache is not stable - (i.e. page that was installed when the symbolic link walk - started might not be in the page cache at the end of the - walk). + follow_link(). The cookie stored by follow_link() is passed + to this method as the last parameter; only called when + cookie isn't NULL. permission: called by the VFS to check for access rights on a POSIX-like filesystem. diff --git a/Documentation/hwmon/tmp401 b/Documentation/hwmon/tmp401 index 8eb88e974055..711f75e189eb 100644 --- a/Documentation/hwmon/tmp401 +++ b/Documentation/hwmon/tmp401 @@ -20,7 +20,7 @@ Supported chips: Datasheet: http://focus.ti.com/docs/prod/folders/print/tmp432.html * Texas Instruments TMP435 Prefix: 'tmp435' - Addresses scanned: I2C 0x37, 0x48 - 0x4f + Addresses scanned: I2C 0x48 - 0x4f Datasheet: http://focus.ti.com/docs/prod/folders/print/tmp435.html Authors: diff --git a/Documentation/i2c/slave-interface b/Documentation/i2c/slave-interface index 389bb5d61854..b228ca54bcf4 100644 --- a/Documentation/i2c/slave-interface +++ b/Documentation/i2c/slave-interface @@ -31,10 +31,10 @@ User manual =========== I2C slave backends behave like standard I2C clients. So, you can instantiate -them like described in the document 'instantiating-devices'. A quick example -for instantiating the slave-eeprom driver from userspace: +them as described in the document 'instantiating-devices'. A quick example for +instantiating the slave-eeprom driver from userspace at address 0x64 on bus 1: - # echo 0-0064 > /sys/bus/i2c/drivers/i2c-slave-eeprom/bind + # echo slave-24c02 0x64 > /sys/bus/i2c/devices/i2c-1/new_device Each backend should come with separate documentation to describe its specific behaviour and setup. diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt index 61ab1628a057..60c9d6d0fd96 100644 --- a/Documentation/kernel-parameters.txt +++ b/Documentation/kernel-parameters.txt @@ -1481,6 +1481,12 @@ bytes respectively. Such letter suffixes can also be entirely omitted. By default, super page will be supported if Intel IOMMU has the capability. With this option, super page will not be supported. + ecs_off [Default Off] + By default, extended context tables will be supported if + the hardware advertises that it has support both for the + extended tables themselves, and also PASID support. With + this option set, extended tables will not be used even + on hardware which claims to support them. intel_idle.max_cstate= [KNL,HW,ACPI,X86] 0 disables intel_idle and fall back on acpi_idle. @@ -2992,11 +2998,34 @@ bytes respectively. Such letter suffixes can also be entirely omitted. Set maximum number of finished RCU callbacks to process in one batch. + rcutree.dump_tree= [KNL] + Dump the structure of the rcu_node combining tree + out at early boot. This is used for diagnostic + purposes, to verify correct tree setup. + + rcutree.gp_cleanup_delay= [KNL] + Set the number of jiffies to delay each step of + RCU grace-period cleanup. This only has effect + when CONFIG_RCU_TORTURE_TEST_SLOW_CLEANUP is set. + rcutree.gp_init_delay= [KNL] Set the number of jiffies to delay each step of RCU grace-period initialization. This only has - effect when CONFIG_RCU_TORTURE_TEST_SLOW_INIT is - set. + effect when CONFIG_RCU_TORTURE_TEST_SLOW_INIT + is set. + + rcutree.gp_preinit_delay= [KNL] + Set the number of jiffies to delay each step of + RCU grace-period pre-initialization, that is, + the propagation of recent CPU-hotplug changes up + the rcu_node combining tree. This only has effect + when CONFIG_RCU_TORTURE_TEST_SLOW_PREINIT is set. + + rcutree.rcu_fanout_exact= [KNL] + Disable autobalancing of the rcu_node combining + tree. This is used by rcutorture, and might + possibly be useful for architectures having high + cache-to-cache transfer latencies. rcutree.rcu_fanout_leaf= [KNL] Increase the number of CPUs assigned to each @@ -3101,7 +3130,11 @@ bytes respectively. Such letter suffixes can also be entirely omitted. test, hence the "fake". rcutorture.nreaders= [KNL] - Set number of RCU readers. + Set number of RCU readers. The value -1 selects + N-1, where N is the number of CPUs. A value + "n" less than -1 selects N-n-2, where N is again + the number of CPUs. For example, -2 selects N + (the number of CPUs), -3 selects N+1, and so on. rcutorture.object_debug= [KNL] Enable debug-object double-call_rcu() testing. diff --git a/Documentation/memory-barriers.txt b/Documentation/memory-barriers.txt index fe4020e4b468..13feb697271f 100644 --- a/Documentation/memory-barriers.txt +++ b/Documentation/memory-barriers.txt @@ -617,16 +617,16 @@ case what's actually required is: However, stores are not speculated. This means that ordering -is- provided for load-store control dependencies, as in the following example: - q = ACCESS_ONCE(a); + q = READ_ONCE_CTRL(a); if (q) { ACCESS_ONCE(b) = p; } -Control dependencies pair normally with other types of barriers. -That said, please note that ACCESS_ONCE() is not optional! Without the -ACCESS_ONCE(), might combine the load from 'a' with other loads from -'a', and the store to 'b' with other stores to 'b', with possible highly -counterintuitive effects on ordering. +Control dependencies pair normally with other types of barriers. That +said, please note that READ_ONCE_CTRL() is not optional! Without the +READ_ONCE_CTRL(), the compiler might combine the load from 'a' with +other loads from 'a', and the store to 'b' with other stores to 'b', +with possible highly counterintuitive effects on ordering. Worse yet, if the compiler is able to prove (say) that the value of variable 'a' is always non-zero, it would be well within its rights @@ -636,12 +636,15 @@ as follows: q = a; b = p; /* BUG: Compiler and CPU can both reorder!!! */ -So don't leave out the ACCESS_ONCE(). +Finally, the READ_ONCE_CTRL() includes an smp_read_barrier_depends() +that DEC Alpha needs in order to respect control depedencies. + +So don't leave out the READ_ONCE_CTRL(). It is tempting to try to enforce ordering on identical stores on both branches of the "if" statement as follows: - q = ACCESS_ONCE(a); + q = READ_ONCE_CTRL(a); if (q) { barrier(); ACCESS_ONCE(b) = p; @@ -655,7 +658,7 @@ branches of the "if" statement as follows: Unfortunately, current compilers will transform this as follows at high optimization levels: - q = ACCESS_ONCE(a); + q = READ_ONCE_CTRL(a); barrier(); ACCESS_ONCE(b) = p; /* BUG: No ordering vs. load from a!!! */ if (q) { @@ -685,7 +688,7 @@ memory barriers, for example, smp_store_release(): In contrast, without explicit memory barriers, two-legged-if control ordering is guaranteed only when the stores differ, for example: - q = ACCESS_ONCE(a); + q = READ_ONCE_CTRL(a); if (q) { ACCESS_ONCE(b) = p; do_something(); @@ -694,14 +697,14 @@ ordering is guaranteed only when the stores differ, for example: do_something_else(); } -The initial ACCESS_ONCE() is still required to prevent the compiler from -proving the value of 'a'. +The initial READ_ONCE_CTRL() is still required to prevent the compiler +from proving the value of 'a'. In addition, you need to be careful what you do with the local variable 'q', otherwise the compiler might be able to guess the value and again remove the needed conditional. For example: - q = ACCESS_ONCE(a); + q = READ_ONCE_CTRL(a); if (q % MAX) { ACCESS_ONCE(b) = p; do_something(); @@ -714,7 +717,7 @@ If MAX is defined to be 1, then the compiler knows that (q % MAX) is equal to zero, in which case the compiler is within its rights to transform the above code into the following: - q = ACCESS_ONCE(a); + q = READ_ONCE_CTRL(a); ACCESS_ONCE(b) = p; do_something_else(); @@ -725,7 +728,7 @@ is gone, and the barrier won't bring it back. Therefore, if you are relying on this ordering, you should make sure that MAX is greater than one, perhaps as follows: - q = ACCESS_ONCE(a); + q = READ_ONCE_CTRL(a); BUILD_BUG_ON(MAX <= 1); /* Order load from a with store to b. */ if (q % MAX) { ACCESS_ONCE(b) = p; @@ -742,14 +745,15 @@ of the 'if' statement. You must also be careful not to rely too much on boolean short-circuit evaluation. Consider this example: - q = ACCESS_ONCE(a); + q = READ_ONCE_CTRL(a); if (a || 1 > 0) ACCESS_ONCE(b) = 1; -Because the second condition is always true, the compiler can transform -this example as following, defeating control dependency: +Because the first condition cannot fault and the second condition is +always true, the compiler can transform this example as following, +defeating control dependency: - q = ACCESS_ONCE(a); + q = READ_ONCE_CTRL(a); ACCESS_ONCE(b) = 1; This example underscores the need to ensure that the compiler cannot @@ -762,8 +766,8 @@ demonstrated by two related examples, with the initial values of x and y both being zero: CPU 0 CPU 1 - ===================== ===================== - r1 = ACCESS_ONCE(x); r2 = ACCESS_ONCE(y); + ======================= ======================= + r1 = READ_ONCE_CTRL(x); r2 = READ_ONCE_CTRL(y); if (r1 > 0) if (r2 > 0) ACCESS_ONCE(y) = 1; ACCESS_ONCE(x) = 1; @@ -783,7 +787,8 @@ But because control dependencies do -not- provide transitivity, the above assertion can fail after the combined three-CPU example completes. If you need the three-CPU example to provide ordering, you will need smp_mb() between the loads and stores in the CPU 0 and CPU 1 code fragments, -that is, just before or just after the "if" statements. +that is, just before or just after the "if" statements. Furthermore, +the original two-CPU example is very fragile and should be avoided. These two examples are the LB and WWC litmus tests from this paper: http://www.cl.cam.ac.uk/users/pes20/ppc-supplemental/test6.pdf and this @@ -791,6 +796,12 @@ site: https://www.cl.cam.ac.uk/~pes20/ppcmem/index.html. In summary: + (*) Control dependencies must be headed by READ_ONCE_CTRL(). + Or, as a much less preferable alternative, interpose + be headed by READ_ONCE() or an ACCESS_ONCE() read and must + have smp_read_barrier_depends() between this read and the + control-dependent write. + (*) Control dependencies can order prior loads against later stores. However, they do -not- guarantee any other sort of ordering: Not prior loads against later loads, nor prior stores against @@ -1784,10 +1795,9 @@ for each construct. These operations all imply certain barriers: Memory operations issued before the ACQUIRE may be completed after the ACQUIRE operation has completed. An smp_mb__before_spinlock(), - combined with a following ACQUIRE, orders prior loads against - subsequent loads and stores and also orders prior stores against - subsequent stores. Note that this is weaker than smp_mb()! The - smp_mb__before_spinlock() primitive is free on many architectures. + combined with a following ACQUIRE, orders prior stores against + subsequent loads and stores. Note that this is weaker than smp_mb()! + The smp_mb__before_spinlock() primitive is free on many architectures. (2) RELEASE operation implication: diff --git a/Documentation/networking/udplite.txt b/Documentation/networking/udplite.txt index d727a3829100..53a726855e49 100644 --- a/Documentation/networking/udplite.txt +++ b/Documentation/networking/udplite.txt @@ -20,7 +20,7 @@ files/UDP-Lite-HOWTO.txt o The Wireshark UDP-Lite WiKi (with capture files): - http://wiki.wireshark.org/Lightweight_User_Datagram_Protocol + https://wiki.wireshark.org/Lightweight_User_Datagram_Protocol o The Protocol Spec, RFC 3828, http://www.ietf.org/rfc/rfc3828.txt diff --git a/Documentation/serial/tty.txt b/Documentation/serial/tty.txt index 1e52d67d0abf..dbe6623fed1c 100644 --- a/Documentation/serial/tty.txt +++ b/Documentation/serial/tty.txt @@ -198,6 +198,9 @@ TTY_IO_ERROR If set, causes all subsequent userspace read/write TTY_OTHER_CLOSED Device is a pty and the other side has closed. +TTY_OTHER_DONE Device is a pty and the other side has closed and + all pending input processing has been completed. + TTY_NO_WRITE_SPLIT Prevent driver from splitting up writes into smaller chunks. diff --git a/Documentation/target/tcmu-design.txt b/Documentation/target/tcmu-design.txt index 43e94ea6d2ca..263b907517ac 100644 --- a/Documentation/target/tcmu-design.txt +++ b/Documentation/target/tcmu-design.txt @@ -15,8 +15,7 @@ Contents: a) Discovering and configuring TCMU uio devices b) Waiting for events on the device(s) c) Managing the command ring -3) Command filtering and pass_level -4) A final note +3) A final note TCM Userspace Design @@ -324,7 +323,7 @@ int handle_device_events(int fd, void *map) /* Process events from cmd ring until we catch up with cmd_head */ while (ent != (void *)mb + mb->cmdr_off + mb->cmd_head) { - if (tcmu_hdr_get_op(&ent->hdr) == TCMU_OP_CMD) { + if (tcmu_hdr_get_op(ent->hdr.len_op) == TCMU_OP_CMD) { uint8_t *cdb = (void *)mb + ent->req.cdb_off; bool success = true; @@ -339,8 +338,12 @@ int handle_device_events(int fd, void *map) ent->rsp.scsi_status = SCSI_CHECK_CONDITION; } } + else if (tcmu_hdr_get_op(ent->hdr.len_op) != TCMU_OP_PAD) { + /* Tell the kernel we didn't handle unknown opcodes */ + ent->hdr.uflags |= TCMU_UFLAG_UNKNOWN_OP; + } else { - /* Do nothing for PAD entries */ + /* Do nothing for PAD entries except update cmd_tail */ } /* update cmd_tail */ @@ -360,28 +363,6 @@ int handle_device_events(int fd, void *map) } -Command filtering and pass_level --------------------------------- - -TCMU supports a "pass_level" option with valid values of 0 or 1. When -the value is 0 (the default), nearly all SCSI commands received for -the device are passed through to the handler. This allows maximum -flexibility but increases the amount of code required by the handler, -to support all mandatory SCSI commands. If pass_level is set to 1, -then only IO-related commands are presented, and the rest are handled -by LIO's in-kernel command emulation. The commands presented at level -1 include all versions of: - -READ -WRITE -WRITE_VERIFY -XDWRITEREAD -WRITE_SAME -COMPARE_AND_WRITE -SYNCHRONIZE_CACHE -UNMAP - - A final note ------------ diff --git a/Documentation/virtual/kvm/mmu.txt b/Documentation/virtual/kvm/mmu.txt index 53838d9c6295..c59bd9bc41ef 100644 --- a/Documentation/virtual/kvm/mmu.txt +++ b/Documentation/virtual/kvm/mmu.txt @@ -169,6 +169,10 @@ Shadow pages contain the following information: Contains the value of cr4.smep && !cr0.wp for which the page is valid (pages for which this is true are different from other pages; see the treatment of cr0.wp=0 below). + role.smap_andnot_wp: + Contains the value of cr4.smap && !cr0.wp for which the page is valid + (pages for which this is true are different from other pages; see the + treatment of cr0.wp=0 below). gfn: Either the guest page table containing the translations shadowed by this page, or the base page frame for linear translations. See role.direct. @@ -344,10 +348,16 @@ on fault type: (user write faults generate a #PF) -In the first case there is an additional complication if CR4.SMEP is -enabled: since we've turned the page into a kernel page, the kernel may now -execute it. We handle this by also setting spte.nx. If we get a user -fetch or read fault, we'll change spte.u=1 and spte.nx=gpte.nx back. +In the first case there are two additional complications: +- if CR4.SMEP is enabled: since we've turned the page into a kernel page, + the kernel may now execute it. We handle this by also setting spte.nx. + If we get a user fetch or read fault, we'll change spte.u=1 and + spte.nx=gpte.nx back. +- if CR4.SMAP is disabled: since the page has been changed to a kernel + page, it can not be reused when CR4.SMAP is enabled. We set + CR4.SMAP && !CR0.WP into shadow page's role to avoid this case. Note, + here we do not care the case that CR4.SMAP is enabled since KVM will + directly inject #PF to guest due to failed permission check. To prevent an spte that was converted into a kernel page with cr0.wp=0 from being written by the kernel after cr0.wp has changed to 1, we make |