<feed xmlns='http://www.w3.org/2005/Atom'>
<title>linux-toradex.git/arch/mips/include, branch v3.19</title>
<subtitle>Linux kernel for Apalis and Colibri modules</subtitle>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/'/>
<entry>
<title>MIPS: Fix syscall_get_nr for the syscall exit tracing.</title>
<updated>2015-02-04T15:40:09+00:00</updated>
<author>
<name>Lars Persson</name>
<email>lars.persson@axis.com</email>
</author>
<published>2015-02-03T16:08:17+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=c2d9f17757310484ab4fd65954f5f9850f6a1349'/>
<id>c2d9f17757310484ab4fd65954f5f9850f6a1349</id>
<content type='text'>
Register 2 is alredy overwritten by the return value when
syscall_trace_leave() is called.

Signed-off-by: Lars Persson &lt;larper@axis.com&gt;
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/9187/
Signed-off-by: Ralf Baechle &lt;ralf@linux-mips.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Register 2 is alredy overwritten by the return value when
syscall_trace_leave() is called.

Signed-off-by: Lars Persson &lt;larper@axis.com&gt;
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/9187/
Signed-off-by: Ralf Baechle &lt;ralf@linux-mips.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>MIPS: mipsregs.h: Add write_32bit_cp1_register()</title>
<updated>2015-01-30T22:04:59+00:00</updated>
<author>
<name>James Hogan</name>
<email>james.hogan@imgtec.com</email>
</author>
<published>2015-01-30T15:40:19+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=5e32033e14ca9c7f7341cb383f5a05699b0b5382'/>
<id>5e32033e14ca9c7f7341cb383f5a05699b0b5382</id>
<content type='text'>
Add a write_32bit_cp1_register() macro to compliment the
read_32bit_cp1_register() macro. This is to abstract whether .set
hardfloat needs to be used based on GAS_HAS_SET_HARDFLOAT.

The implementation of _read_32bit_cp1_register() .sets mips1 due to
failure of gas v2.19 to assemble cfc1 for Octeon (see commit
25c300030016 ("MIPS: Override assembler target architecture for
octeon.")). I haven't copied this over to _write_32bit_cp1_register() as
I'm uncertain whether it applies to ctc1 too, or whether anybody cares
about that version of binutils any longer.

Signed-off-by: James Hogan &lt;james.hogan@imgtec.com&gt;
Cc: Ralf Baechle &lt;ralf@linux-mips.org&gt;
Cc: Paul Burton &lt;paul.burton@imgtec.com&gt;
Cc: David Daney &lt;david.daney@cavium.com&gt;
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/9172/
Signed-off-by: Ralf Baechle &lt;ralf@linux-mips.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Add a write_32bit_cp1_register() macro to compliment the
read_32bit_cp1_register() macro. This is to abstract whether .set
hardfloat needs to be used based on GAS_HAS_SET_HARDFLOAT.

The implementation of _read_32bit_cp1_register() .sets mips1 due to
failure of gas v2.19 to assemble cfc1 for Octeon (see commit
25c300030016 ("MIPS: Override assembler target architecture for
octeon.")). I haven't copied this over to _write_32bit_cp1_register() as
I'm uncertain whether it applies to ctc1 too, or whether anybody cares
about that version of binutils any longer.

Signed-off-by: James Hogan &lt;james.hogan@imgtec.com&gt;
Cc: Ralf Baechle &lt;ralf@linux-mips.org&gt;
Cc: Paul Burton &lt;paul.burton@imgtec.com&gt;
Cc: David Daney &lt;david.daney@cavium.com&gt;
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/9172/
Signed-off-by: Ralf Baechle &lt;ralf@linux-mips.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>MIPS: ARC: Fix build error.</title>
<updated>2015-01-19T12:09:52+00:00</updated>
<author>
<name>Ralf Baechle</name>
<email>ralf@linux-mips.org</email>
</author>
<published>2015-01-19T11:53:49+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=93000719491581990a8a1094eaadbf3bdccf2a5f'/>
<id>93000719491581990a8a1094eaadbf3bdccf2a5f</id>
<content type='text'>
[...]
 struct component {
        ^
In file included from ./arch/mips/include/asm/sn/klconfig.h:58:0,
                 from ./arch/mips/include/asm/sn/module.h:12,
                 from ./arch/mips/include/asm/sn/node.h:8,
                 from ./arch/mips/include/asm/mach-ip35/mmzone.h:4,
                 from ./arch/mips/include/asm/mmzone.h:9,
                 from ./arch/mips/include/asm/mach-ip35/topology.h:7,
                 from ./arch/mips/include/asm/topology.h:11,
                 from include/linux/topology.h:35,
                 from include/linux/gfp.h:8,
                 from include/linux/device.h:29,
                 from drivers/base/component.c:14:
./arch/mips/include/asm/fw/arc/hinv.h:122:16: note: originally defined here
 typedef struct component {
                ^
make[2]: *** [drivers/base/component.o] Error 1
make[2]: Target `__build' not remade because of errors.
make[1]: *** [drivers/base] Error 2
make[1]: Target `__build' not remade because of errors.

Fix by using an nameless struct definition in the COMPONENT definition.
Which is what the ARC spec uses anyway.  While at it, do the same thing
for two other typedefs.

Signed-off-by: Ralf Baechle &lt;ralf@linux-mips.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
[...]
 struct component {
        ^
In file included from ./arch/mips/include/asm/sn/klconfig.h:58:0,
                 from ./arch/mips/include/asm/sn/module.h:12,
                 from ./arch/mips/include/asm/sn/node.h:8,
                 from ./arch/mips/include/asm/mach-ip35/mmzone.h:4,
                 from ./arch/mips/include/asm/mmzone.h:9,
                 from ./arch/mips/include/asm/mach-ip35/topology.h:7,
                 from ./arch/mips/include/asm/topology.h:11,
                 from include/linux/topology.h:35,
                 from include/linux/gfp.h:8,
                 from include/linux/device.h:29,
                 from drivers/base/component.c:14:
./arch/mips/include/asm/fw/arc/hinv.h:122:16: note: originally defined here
 typedef struct component {
                ^
make[2]: *** [drivers/base/component.o] Error 1
make[2]: Target `__build' not remade because of errors.
make[1]: *** [drivers/base] Error 2
make[1]: Target `__build' not remade because of errors.

Fix by using an nameless struct definition in the COMPONENT definition.
Which is what the ARC spec uses anyway.  While at it, do the same thing
for two other typedefs.

Signed-off-by: Ralf Baechle &lt;ralf@linux-mips.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>MIPS: mips-cm: Fix sparse warnings</title>
<updated>2015-01-13T14:53:09+00:00</updated>
<author>
<name>James Hogan</name>
<email>james.hogan@imgtec.com</email>
</author>
<published>2015-01-05T15:45:30+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=50083928bcb38bc847cb885fd70f79a63cabd9b5'/>
<id>50083928bcb38bc847cb885fd70f79a63cabd9b5</id>
<content type='text'>
Sparse emits a bunch of warnings in mips-cm.h due to casting away of
__iomem by the addr_gcr_*() functions:

arch/mips/include/asm/mips-cm.h:134:1: warning: cast removes address space of expression

And subsequent passing of the return values to __raw_readl() and
__raw_writel() in the read_gcr_*() and write_gcr_*() functions:

arch/mips/include/asm/mips-cm.h:134:1: warning: incorrect type in argument 2 (different address spaces)
arch/mips/include/asm/mips-cm.h:134:1:    expected void volatile [noderef] &lt;asn:2&gt;*mem
arch/mips/include/asm/mips-cm.h:134:1:    got unsigned int [usertype] *
arch/mips/include/asm/mips-cm.h:134:1: warning: incorrect type in argument 1 (different address spaces)
arch/mips/include/asm/mips-cm.h:134:1:    expected void const volatile [noderef] &lt;asn:2&gt;*mem
arch/mips/include/asm/mips-cm.h:134:1:    got unsigned int [usertype] *

Fix by adding __iomem to the addr_gcr_*() return type and cast.

Signed-off-by: James Hogan &lt;james.hogan@imgtec.com&gt;
Cc: Paul Burton &lt;paul.burton@imgtec.com&gt;
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/8874/
Signed-off-by: Ralf Baechle &lt;ralf@linux-mips.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Sparse emits a bunch of warnings in mips-cm.h due to casting away of
__iomem by the addr_gcr_*() functions:

arch/mips/include/asm/mips-cm.h:134:1: warning: cast removes address space of expression

And subsequent passing of the return values to __raw_readl() and
__raw_writel() in the read_gcr_*() and write_gcr_*() functions:

arch/mips/include/asm/mips-cm.h:134:1: warning: incorrect type in argument 2 (different address spaces)
arch/mips/include/asm/mips-cm.h:134:1:    expected void volatile [noderef] &lt;asn:2&gt;*mem
arch/mips/include/asm/mips-cm.h:134:1:    got unsigned int [usertype] *
arch/mips/include/asm/mips-cm.h:134:1: warning: incorrect type in argument 1 (different address spaces)
arch/mips/include/asm/mips-cm.h:134:1:    expected void const volatile [noderef] &lt;asn:2&gt;*mem
arch/mips/include/asm/mips-cm.h:134:1:    got unsigned int [usertype] *

Fix by adding __iomem to the addr_gcr_*() return type and cast.

Signed-off-by: James Hogan &lt;james.hogan@imgtec.com&gt;
Cc: Paul Burton &lt;paul.burton@imgtec.com&gt;
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/8874/
Signed-off-by: Ralf Baechle &lt;ralf@linux-mips.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>MIPS: Wire up execveat(2).</title>
<updated>2015-01-13T14:53:09+00:00</updated>
<author>
<name>Ralf Baechle</name>
<email>ralf@linux-mips.org</email>
</author>
<published>2014-12-17T11:34:04+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=389cdc5d359c48c36c3512645ec2533370aa6eb3'/>
<id>389cdc5d359c48c36c3512645ec2533370aa6eb3</id>
<content type='text'>
Signed-off-by: Ralf Baechle &lt;ralf@linux-mips.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Signed-off-by: Ralf Baechle &lt;ralf@linux-mips.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>MIPS: FRE: Use set/clear_c0_config5 instead of open coded sequences.</title>
<updated>2015-01-13T14:53:08+00:00</updated>
<author>
<name>Ralf Baechle</name>
<email>ralf@linux-mips.org</email>
</author>
<published>2014-12-17T10:46:40+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=d33e6fe3ca74108e8e6ea1f5560b21c834b579a5'/>
<id>d33e6fe3ca74108e8e6ea1f5560b21c834b579a5</id>
<content type='text'>
Signed-off-by: Ralf Baechle &lt;ralf@linux-mips.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Signed-off-by: Ralf Baechle &lt;ralf@linux-mips.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>MIPS: Do not fiddle with FRE unless FRE is actually available.</title>
<updated>2015-01-13T14:53:08+00:00</updated>
<author>
<name>Ralf Baechle</name>
<email>ralf@linux-mips.org</email>
</author>
<published>2014-12-17T10:39:30+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=b0c34f6155e2d8bbe096a85a770d63ee6be6c726'/>
<id>b0c34f6155e2d8bbe096a85a770d63ee6be6c726</id>
<content type='text'>
Commit 4227a2d4efc9c84f35826dc4d1e6dc183f6c1c05 (MIPS: Support for hybrid
FPRs) changes the kernel to execute read_c0_config5() even on processors
that don't have a Config5 register.  According to the arch spec the
behaviour of trying to read or write this register is UNDEFINED where this
register doesn't exist, that is merely looking at this register is
already cruel because that might kill a kitten.

In case of Qemu older than v2.2 Qemu has elected to implement this
UNDEFINED behaviour by taking a RI exception - which then fries the
kernel:

[...]
Freeing YAMON memory: 956k freed
Freeing unused kernel memory: 240K (80674000 - 806b0000)
Reserved instruction in kernel code[#1]:
CPU: 0 PID: 1 Comm: init Not tainted 3.18.0-rc6-00058-g4227a2d #26
task: 86047588 ti: 86048000 task.ti: 86048000
$ 0   : 00000000 77a638cc 00000000 00000000
[...]

For qemu v2.2.0 commit f31b035a9f10dc9b57f01c426110af845d453ce2
(target-mips: correctly handle access to unimplemented CP0 register)
changed the behaviour to returning zero on read and ignoring writes
which more matches how typical hardware implementations actually behave.

Signed-off-by: Ralf Baechle &lt;ralf@linux-mips.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Commit 4227a2d4efc9c84f35826dc4d1e6dc183f6c1c05 (MIPS: Support for hybrid
FPRs) changes the kernel to execute read_c0_config5() even on processors
that don't have a Config5 register.  According to the arch spec the
behaviour of trying to read or write this register is UNDEFINED where this
register doesn't exist, that is merely looking at this register is
already cruel because that might kill a kitten.

In case of Qemu older than v2.2 Qemu has elected to implement this
UNDEFINED behaviour by taking a RI exception - which then fries the
kernel:

[...]
Freeing YAMON memory: 956k freed
Freeing unused kernel memory: 240K (80674000 - 806b0000)
Reserved instruction in kernel code[#1]:
CPU: 0 PID: 1 Comm: init Not tainted 3.18.0-rc6-00058-g4227a2d #26
task: 86047588 ti: 86048000 task.ti: 86048000
$ 0   : 00000000 77a638cc 00000000 00000000
[...]

For qemu v2.2.0 commit f31b035a9f10dc9b57f01c426110af845d453ce2
(target-mips: correctly handle access to unimplemented CP0 register)
changed the behaviour to returning zero on read and ignoring writes
which more matches how typical hardware implementations actually behave.

Signed-off-by: Ralf Baechle &lt;ralf@linux-mips.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net</title>
<updated>2014-12-13T00:11:12+00:00</updated>
<author>
<name>Linus Torvalds</name>
<email>torvalds@linux-foundation.org</email>
</author>
<published>2014-12-13T00:11:12+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=f96fe225677b3efb74346ebd56fafe3997b02afa'/>
<id>f96fe225677b3efb74346ebd56fafe3997b02afa</id>
<content type='text'>
Pull another networking update from David Miller:
 "Small follow-up to the main merge pull from the other day:

  1) Alexander Duyck's DMA memory barrier patch set.

  2) cxgb4 driver fixes from Karen Xie.

  3) Add missing export of fixed_phy_register() to modules, from Mark
     Salter.

  4) DSA bug fixes from Florian Fainelli"

* git://git.kernel.org/pub/scm/linux/kernel/git/davem/net: (24 commits)
  net/macb: add TX multiqueue support for gem
  linux/interrupt.h: remove the definition of unused tasklet_hi_enable
  jme: replace calls to redundant function
  net: ethernet: davicom: Allow to select DM9000 for nios2
  net: ethernet: smsc: Allow to select SMC91X for nios2
  cxgb4: Add support for QSA modules
  libcxgbi: fix freeing skb prematurely
  cxgb4i: use set_wr_txq() to set tx queues
  cxgb4i: handle non-pdu-aligned rx data
  cxgb4i: additional types of negative advice
  cxgb4/cxgb4i: set the max. pdu length in firmware
  cxgb4i: fix credit check for tx_data_wr
  cxgb4i: fix tx immediate data credit check
  net: phy: export fixed_phy_register()
  fib_trie: Fix trie balancing issue if new node pushes down existing node
  vlan: Add ability to always enable TSO/UFO
  r8169:update rtl8168g pcie ephy parameter
  net: dsa: bcm_sf2: force link for all fixed PHY devices
  fm10k/igb/ixgbe: Use dma_rmb on Rx descriptor reads
  r8169: Use dma_rmb() and dma_wmb() for DescOwn checks
  ...
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Pull another networking update from David Miller:
 "Small follow-up to the main merge pull from the other day:

  1) Alexander Duyck's DMA memory barrier patch set.

  2) cxgb4 driver fixes from Karen Xie.

  3) Add missing export of fixed_phy_register() to modules, from Mark
     Salter.

  4) DSA bug fixes from Florian Fainelli"

* git://git.kernel.org/pub/scm/linux/kernel/git/davem/net: (24 commits)
  net/macb: add TX multiqueue support for gem
  linux/interrupt.h: remove the definition of unused tasklet_hi_enable
  jme: replace calls to redundant function
  net: ethernet: davicom: Allow to select DM9000 for nios2
  net: ethernet: smsc: Allow to select SMC91X for nios2
  cxgb4: Add support for QSA modules
  libcxgbi: fix freeing skb prematurely
  cxgb4i: use set_wr_txq() to set tx queues
  cxgb4i: handle non-pdu-aligned rx data
  cxgb4i: additional types of negative advice
  cxgb4/cxgb4i: set the max. pdu length in firmware
  cxgb4i: fix credit check for tx_data_wr
  cxgb4i: fix tx immediate data credit check
  net: phy: export fixed_phy_register()
  fib_trie: Fix trie balancing issue if new node pushes down existing node
  vlan: Add ability to always enable TSO/UFO
  r8169:update rtl8168g pcie ephy parameter
  net: dsa: bcm_sf2: force link for all fixed PHY devices
  fm10k/igb/ixgbe: Use dma_rmb on Rx descriptor reads
  r8169: Use dma_rmb() and dma_wmb() for DescOwn checks
  ...
</pre>
</div>
</content>
</entry>
<entry>
<title>arch: Add lightweight memory barriers dma_rmb() and dma_wmb()</title>
<updated>2014-12-12T02:15:06+00:00</updated>
<author>
<name>Alexander Duyck</name>
<email>alexander.h.duyck@redhat.com</email>
</author>
<published>2014-12-11T23:02:06+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=1077fa36f23e259858caf6f269a47393a5aff523'/>
<id>1077fa36f23e259858caf6f269a47393a5aff523</id>
<content type='text'>
There are a number of situations where the mandatory barriers rmb() and
wmb() are used to order memory/memory operations in the device drivers
and those barriers are much heavier than they actually need to be.  For
example in the case of PowerPC wmb() calls the heavy-weight sync
instruction when for coherent memory operations all that is really needed
is an lsync or eieio instruction.

This commit adds a coherent only version of the mandatory memory barriers
rmb() and wmb().  In most cases this should result in the barrier being the
same as the SMP barriers for the SMP case, however in some cases we use a
barrier that is somewhere in between rmb() and smp_rmb().  For example on
ARM the rmb barriers break down as follows:

  Barrier   Call     Explanation
  --------- -------- ----------------------------------
  rmb()     dsb()    Data synchronization barrier - system
  dma_rmb() dmb(osh) data memory barrier - outer sharable
  smp_rmb() dmb(ish) data memory barrier - inner sharable

These new barriers are not as safe as the standard rmb() and wmb().
Specifically they do not guarantee ordering between coherent and incoherent
memories.  The primary use case for these would be to enforce ordering of
reads and writes when accessing coherent memory that is shared between the
CPU and a device.

It may also be noted that there is no dma_mb().  Most architectures don't
provide a good mechanism for performing a coherent only full barrier without
resorting to the same mechanism used in mb().  As such there isn't much to
be gained in trying to define such a function.

Cc: Frederic Weisbecker &lt;fweisbec@gmail.com&gt;
Cc: Mathieu Desnoyers &lt;mathieu.desnoyers@polymtl.ca&gt;
Cc: Michael Ellerman &lt;michael@ellerman.id.au&gt;
Cc: Michael Neuling &lt;mikey@neuling.org&gt;
Cc: Russell King &lt;linux@arm.linux.org.uk&gt;
Cc: Geert Uytterhoeven &lt;geert@linux-m68k.org&gt;
Cc: Heiko Carstens &lt;heiko.carstens@de.ibm.com&gt;
Cc: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
Cc: Martin Schwidefsky &lt;schwidefsky@de.ibm.com&gt;
Cc: Tony Luck &lt;tony.luck@intel.com&gt;
Cc: Oleg Nesterov &lt;oleg@redhat.com&gt;
Cc: "Paul E. McKenney" &lt;paulmck@linux.vnet.ibm.com&gt;
Cc: Peter Zijlstra &lt;peterz@infradead.org&gt;
Cc: Ingo Molnar &lt;mingo@kernel.org&gt;
Cc: David Miller &lt;davem@davemloft.net&gt;
Acked-by: Benjamin Herrenschmidt &lt;benh@kernel.crashing.org&gt;
Acked-by: Will Deacon &lt;will.deacon@arm.com&gt;
Signed-off-by: Alexander Duyck &lt;alexander.h.duyck@redhat.com&gt;
Signed-off-by: David S. Miller &lt;davem@davemloft.net&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
There are a number of situations where the mandatory barriers rmb() and
wmb() are used to order memory/memory operations in the device drivers
and those barriers are much heavier than they actually need to be.  For
example in the case of PowerPC wmb() calls the heavy-weight sync
instruction when for coherent memory operations all that is really needed
is an lsync or eieio instruction.

This commit adds a coherent only version of the mandatory memory barriers
rmb() and wmb().  In most cases this should result in the barrier being the
same as the SMP barriers for the SMP case, however in some cases we use a
barrier that is somewhere in between rmb() and smp_rmb().  For example on
ARM the rmb barriers break down as follows:

  Barrier   Call     Explanation
  --------- -------- ----------------------------------
  rmb()     dsb()    Data synchronization barrier - system
  dma_rmb() dmb(osh) data memory barrier - outer sharable
  smp_rmb() dmb(ish) data memory barrier - inner sharable

These new barriers are not as safe as the standard rmb() and wmb().
Specifically they do not guarantee ordering between coherent and incoherent
memories.  The primary use case for these would be to enforce ordering of
reads and writes when accessing coherent memory that is shared between the
CPU and a device.

It may also be noted that there is no dma_mb().  Most architectures don't
provide a good mechanism for performing a coherent only full barrier without
resorting to the same mechanism used in mb().  As such there isn't much to
be gained in trying to define such a function.

Cc: Frederic Weisbecker &lt;fweisbec@gmail.com&gt;
Cc: Mathieu Desnoyers &lt;mathieu.desnoyers@polymtl.ca&gt;
Cc: Michael Ellerman &lt;michael@ellerman.id.au&gt;
Cc: Michael Neuling &lt;mikey@neuling.org&gt;
Cc: Russell King &lt;linux@arm.linux.org.uk&gt;
Cc: Geert Uytterhoeven &lt;geert@linux-m68k.org&gt;
Cc: Heiko Carstens &lt;heiko.carstens@de.ibm.com&gt;
Cc: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
Cc: Martin Schwidefsky &lt;schwidefsky@de.ibm.com&gt;
Cc: Tony Luck &lt;tony.luck@intel.com&gt;
Cc: Oleg Nesterov &lt;oleg@redhat.com&gt;
Cc: "Paul E. McKenney" &lt;paulmck@linux.vnet.ibm.com&gt;
Cc: Peter Zijlstra &lt;peterz@infradead.org&gt;
Cc: Ingo Molnar &lt;mingo@kernel.org&gt;
Cc: David Miller &lt;davem@davemloft.net&gt;
Acked-by: Benjamin Herrenschmidt &lt;benh@kernel.crashing.org&gt;
Acked-by: Will Deacon &lt;will.deacon@arm.com&gt;
Signed-off-by: Alexander Duyck &lt;alexander.h.duyck@redhat.com&gt;
Signed-off-by: David S. Miller &lt;davem@davemloft.net&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>arch: Cleanup read_barrier_depends() and comments</title>
<updated>2014-12-12T02:15:05+00:00</updated>
<author>
<name>Alexander Duyck</name>
<email>alexander.h.duyck@redhat.com</email>
</author>
<published>2014-12-11T23:01:55+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=8a449718414ff10b9d5559ed3e8e09c7178774f2'/>
<id>8a449718414ff10b9d5559ed3e8e09c7178774f2</id>
<content type='text'>
This patch is meant to cleanup the handling of read_barrier_depends and
smp_read_barrier_depends.  In multiple spots in the kernel headers
read_barrier_depends is defined as "do {} while (0)", however we then go
into the SMP vs non-SMP sections and have the SMP version reference
read_barrier_depends, and the non-SMP define it as yet another empty
do/while.

With this commit I went through and cleaned out the duplicate definitions
and reduced the number of definitions down to 2 per header.  In addition I
moved the 50 line comments for the macro from the x86 and mips headers that
defined it as an empty do/while to those that were actually defining the
macro, alpha and blackfin.

Signed-off-by: Alexander Duyck &lt;alexander.h.duyck@redhat.com&gt;
Signed-off-by: David S. Miller &lt;davem@davemloft.net&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
This patch is meant to cleanup the handling of read_barrier_depends and
smp_read_barrier_depends.  In multiple spots in the kernel headers
read_barrier_depends is defined as "do {} while (0)", however we then go
into the SMP vs non-SMP sections and have the SMP version reference
read_barrier_depends, and the non-SMP define it as yet another empty
do/while.

With this commit I went through and cleaned out the duplicate definitions
and reduced the number of definitions down to 2 per header.  In addition I
moved the 50 line comments for the macro from the x86 and mips headers that
defined it as an empty do/while to those that were actually defining the
macro, alpha and blackfin.

Signed-off-by: Alexander Duyck &lt;alexander.h.duyck@redhat.com&gt;
Signed-off-by: David S. Miller &lt;davem@davemloft.net&gt;
</pre>
</div>
</content>
</entry>
</feed>
