linux-toradex.git/drivers/s390/char, branch v5.0

s390/smp: fix CPU hotplug deadlock with CPU rescan

2019-01-11T16:12:02+00:00

smp_rescan_cpus() is called without the device_hotplug_lock, which can lead
to a dedlock when a new CPU is found and immediately set online by a udev
rule.

This was observed on an older kernel version, where the cpu_hotplug_begin()
loop was still present, and it resulted in hanging chcpu and systemd-udev
processes. This specific deadlock will not show on current kernels. However,
there may be other possible deadlocks, and since smp_rescan_cpus() can still
trigger a CPU hotplug operation, the device_hotplug_lock should be held.

For reference, this was the deadlock with the old cpu_hotplug_begin() loop:

        chcpu (rescan)                       systemd-udevd

 echo 1 > /sys/../rescan
 -> smp_rescan_cpus()
 -> (*) get_online_cpus()
    (increases refcount)
 -> smp_add_present_cpu()
    (new CPU found)
 -> register_cpu()
 -> device_add()
 -> udev "add" event triggered -----------> udev rule sets CPU online
                                         -> echo 1 > /sys/.../online
                                         -> lock_device_hotplug_sysfs()
                                            (this is missing in rescan path)
                                         -> device_online()
                                         -> (**) device_lock(new CPU dev)
                                         -> cpu_up()
                                         -> cpu_hotplug_begin()
                                            (loops until refcount == 0)
                                            -> deadlock with (*)
 -> bus_probe_device()
 -> device_attach()
 -> device_lock(new CPU dev)
    -> deadlock with (**)

Fix this by taking the device_hotplug_lock in the CPU rescan path.

Cc: 
Signed-off-by: Gerald Schaefer 
Signed-off-by: Martin Schwidefsky

s390/drivers: fix proc/debugfs file permissions

2018-12-13T09:42:24+00:00

Remove write permissions for fops without a write callback.

Signed-off-by: Sebastian Ott 
Signed-off-by: Martin Schwidefsky

mm: remove include/linux/bootmem.h

2018-10-31T15:54:16+00:00

Move remaining definitions and declarations from include/linux/bootmem.h
into include/linux/memblock.h and remove the redundant header.

The includes were replaced with the semantic patch below and then
semi-automated removal of duplicated '#include 

@@
@@
- #include 
+ #include 

[sfr@canb.auug.org.au: dma-direct: fix up for the removal of linux/bootmem.h]
  Link: http://lkml.kernel.org/r/20181002185342.133d1680@canb.auug.org.au
[sfr@canb.auug.org.au: powerpc: fix up for removal of linux/bootmem.h]
  Link: http://lkml.kernel.org/r/20181005161406.73ef8727@canb.auug.org.au
[sfr@canb.auug.org.au: x86/kaslr, ACPI/NUMA: fix for linux/bootmem.h removal]
  Link: http://lkml.kernel.org/r/20181008190341.5e396491@canb.auug.org.au
Link: http://lkml.kernel.org/r/1536927045-23536-30-git-send-email-rppt@linux.vnet.ibm.com
Signed-off-by: Mike Rapoport 
Signed-off-by: Stephen Rothwell 
Acked-by: Michal Hocko 
Cc: Catalin Marinas 
Cc: Chris Zankel 
Cc: "David S. Miller" 
Cc: Geert Uytterhoeven 
Cc: Greentime Hu 
Cc: Greg Kroah-Hartman 
Cc: Guan Xuetao 
Cc: Ingo Molnar 
Cc: "James E.J. Bottomley" 
Cc: Jonas Bonn 
Cc: Jonathan Corbet 
Cc: Ley Foon Tan 
Cc: Mark Salter 
Cc: Martin Schwidefsky 
Cc: Matt Turner 
Cc: Michael Ellerman 
Cc: Michal Simek 
Cc: Palmer Dabbelt 
Cc: Paul Burton 
Cc: Richard Kuo 
Cc: Richard Weinberger 
Cc: Rich Felker 
Cc: Russell King 
Cc: Serge Semin 
Cc: Thomas Gleixner 
Cc: Tony Luck 
Cc: Vineet Gupta 
Cc: Yoshinori Sato 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

s390/kasan: avoid instrumentation of early C code

2018-10-09T09:21:17+00:00

Instrumented C code cannot run without the kasan shadow area. Exempt
source code files from kasan which are running before / used during
kasan initialization.

Reviewed-by: Martin Schwidefsky 
Signed-off-by: Vasily Gorbik 
Signed-off-by: Martin Schwidefsky

s390/sclp: introduce sclp_early_get_hsa_size

2018-10-09T09:21:13+00:00

Introduce sclp_early_get_hsa_size function to be used during early
memory detection. This function allows to find a memory limit imposed
during zfcpdump.

Reviewed-by: Heiko Carstens 
Reviewed-by: Martin Schwidefsky 
Signed-off-by: Vasily Gorbik 
Signed-off-by: Martin Schwidefsky

s390/mem_detect: replace tprot loop with binary search

2018-10-09T09:21:12+00:00

In a situation when other memory detection methods are not available
(no SCLP and no z/VM diag260), continuous online memory is assumed.
Replacing tprot loop with faster binary search, as only online memory
end has to be found.

Reviewed-by: Heiko Carstens 
Reviewed-by: Martin Schwidefsky 
Signed-off-by: Vasily Gorbik 
Signed-off-by: Martin Schwidefsky

s390/mem_detect: introduce SCLP storage info

2018-10-09T09:21:09+00:00

SCLP storage info allows to detect continuous and non-continuous online
memory under LPAR, z/VM and KVM, when standby memory is defined.

Reviewed-by: Heiko Carstens 
Reviewed-by: Martin Schwidefsky 
Signed-off-by: Vasily Gorbik 
Signed-off-by: Martin Schwidefsky

s390/mem_detect: move tprot loop to early boot phase

2018-10-09T09:21:08+00:00

Move memory detection to early boot phase. To store online memory
regions "struct mem_detect_info" has been introduced together with
for_each_mem_detect_block iterator. mem_detect_info is later converted
to memblock.

Also introduces sclp_early_get_meminfo function to get maximum physical
memory and maximum increment number.

Reviewed-by: Heiko Carstens 
Reviewed-by: Martin Schwidefsky 
Signed-off-by: Vasily Gorbik 
Signed-off-by: Martin Schwidefsky

s390/sclp: move sclp_early_read_info to sclp_early_core.c

2018-10-09T09:21:07+00:00

To enable early online memory detection sclp_early_read_info has
been moved to sclp_early_core.c. sclp_info_sccb has been made a part
of .boot.data, which allows to reuse it later during early kernel
startup and make sclp_early_read_info call just once.

Reviewed-by: Heiko Carstens 
Reviewed-by: Martin Schwidefsky 
Signed-off-by: Vasily Gorbik 
Signed-off-by: Martin Schwidefsky

s390/sclp: simplify early hsa_size detection

2018-10-09T09:21:04+00:00

Architecture documentation suggests that hsa_size has been available in
the read info since the list-directed ipl dump has been introduced. By
using this value few early sclp calls could be avoided.

Reviewed-by: Heiko Carstens 
Reviewed-by: Martin Schwidefsky 
Signed-off-by: Vasily Gorbik 
Signed-off-by: Martin Schwidefsky