aacraid: Relinquish CPU during timeout wait
authorRaghava Aditya Renukunta <RaghavaAditya.Renukunta@microsemi.com>
Tue, 26 Apr 2016 06:31:26 +0000 (23:31 -0700)
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Wed, 8 Jun 2016 01:14:33 +0000 (18:14 -0700)
commit9a5ca989b54975b40915bc6fa5c909cf11f90c62
treee569f373db3f78a643e5be1bcb756ac1eb85f838
parent04a6bcca2f76f7aa5b8749644e3a2947a3cf040d
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()"
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: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
drivers/scsi/aacraid/commsup.c