pstore/core: drop cmpxchg based updates
authorSebastian Andrzej Siewior <bigeasy@linutronix.de>
Thu, 8 Sep 2016 11:48:06 +0000 (13:48 +0200)
committerKees Cook <keescook@chromium.org>
Thu, 8 Sep 2016 22:00:47 +0000 (15:00 -0700)
commitd5a9bf0b38d2ac85c9a693c7fb851f74fd2a2494
tree223697a08dc1c7209ed40545bb5561ca4c23c6dc
parent4407de74df18ed405cc5998990004c813ccfdbde
pstore/core: drop cmpxchg based updates

I have here a FPGA behind PCIe which exports SRAM which I use for
pstore. Now it seems that the FPGA no longer supports cmpxchg based
updates and writes back 0xff…ff and returns the same.  This leads to
crash during crash rendering pstore useless.
Since I doubt that there is much benefit from using cmpxchg() here, I am
dropping this atomic access and use the spinlock based version.

Cc: Anton Vorontsov <anton@enomsg.org>
Cc: Colin Cross <ccross@android.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Rabin Vincent <rabinv@axis.com>
Tested-by: Rabin Vincent <rabinv@axis.com>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
[kees: remove "_locked" suffix since it's the only option now]
Signed-off-by: Kees Cook <keescook@chromium.org>
Cc: stable@vger.kernel.org
fs/pstore/ram_core.c