[v2] powerpc/fadump: Fix the race in crash_fadump().

[Michael Ellerman]

On Mon, 2016-10-24 at 18:21:51 UTC, Mahesh Salgaonkar wrote:
> From: Mahesh Salgaonkar <mahesh at linux.vnet.ibm.com>
> 
> There are chances that multiple CPUs can call crash_fadump() simultaneously
> and would start duplicating same info to vmcoreinfo ELF note section. This
> causes makedumpfile to fail during kdump capture. One example is,
> triggering dumprestart from HMC which sends system reset to all the CPUs at
> once.
> 
> makedumpfile --dump-dmesg /proc/vmcore
> read_vmcoreinfo_basic_info: Invalid data in /tmp/vmcoreinfoyjgxlL: CRASHTIME=1475605971CRASHTIME=1475605971CRASHTIME=1475605971CRASHTIME=1475605971CRASHTIME=1475605971CRASHTIME=1475605971CRASHTIME=1475605971CRASHTIME=1475605971
> makedumpfile Failed.
> Running makedumpfile --dump-dmesg /proc/vmcore failed (1).
> 
> makedumpfile  -d 31 -l /proc/vmcore
> read_vmcoreinfo_basic_info: Invalid data in /tmp/vmcoreinfo1mmVdO: CRASHTIME=1475605971CRASHTIME=1475605971CRASHTIME=1475605971CRASHTIME=1475605971CRASHTIME=1475605971CRASHTIME=1475605971CRASHTIME=1475605971CRASHTIME=1475605971
> makedumpfile Failed.
> Running makedumpfile  -d 31 -l /proc/vmcore failed (1).
> 
> Signed-off-by: Mahesh Salgaonkar <mahesh at linux.vnet.ibm.com>

Applied to powerpc next, thanks.

https://git.kernel.org/powerpc/c/f2a5e8f0023eba847ad2adb145b2f6

cheers