aacraid: Relinquish CPU during timeout wait
authorRaghava Aditya Renukunta <RaghavaAditya.Renukunta@microsemi.com>
Tue, 26 Apr 2016 06:31:26 +0000 (23:31 -0700)
committerWilly Tarreau <w@1wt.eu>
Sun, 21 Aug 2016 21:22:43 +0000 (23:22 +0200)
commit4f362654ca19157b9191143823061d963a0318d7
tree8d0c9def26d9a8fe26dcd85ec4ad6436cf53ca16
parent5b26ade36bce58a17e2411082e8e45db213bdd28
aacraid: Relinquish CPU during timeout wait

commit 07beca2be24cc710461c0b131832524c9ee08910 upstream.

aac_fib_send has a special function case for initial commands during
driver initialization using wait < 0(pseudo sync mode). In this case,
the command does not sleep but rather spins checking for timeout.This
loop is calls cpu_relax() in an attempt to allow other processes/threads
to use the CPU, but this function does not relinquish the CPU and so the
command will hog the processor. This was observed in a KDUMP
"crashkernel" and that prevented the "command thread" (which is
responsible for completing the command from being timed out) from
starting because it could not get the CPU.

Fixed by replacing "cpu_relax()" call with "schedule()"
Cc: stable@vger.kernel.org
Signed-off-by: Raghava Aditya Renukunta <RaghavaAditya.Renukunta@microsemi.com>
Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Willy Tarreau <w@1wt.eu>
drivers/scsi/aacraid/commsup.c