From 43ca60457b15da343097c28d53eb6178bd7dd14c Mon Sep 17 00:00:00 2001 From: Raghava Aditya Renukunta Date: Mon, 25 Apr 2016 23:31:26 -0700 Subject: [PATCH] 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 Reviewed-by: Johannes Thumshirn Signed-off-by: Martin K. Petersen Signed-off-by: Jiri Slaby --- drivers/scsi/aacraid/commsup.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) diff --git a/drivers/scsi/aacraid/commsup.c b/drivers/scsi/aacraid/commsup.c index 6b32ddcefc11..06f73d2c878c 100644 --- a/drivers/scsi/aacraid/commsup.c +++ b/drivers/scsi/aacraid/commsup.c @@ -590,10 +590,10 @@ int aac_fib_send(u16 command, struct fib *fibptr, unsigned long size, } return -EFAULT; } - /* We used to udelay() here but that absorbed - * a CPU when a timeout occured. Not very - * useful. */ - cpu_relax(); + /* + * Allow other processes / CPUS to use core + */ + schedule(); } } else if (down_interruptible(&fibptr->event_wait)) { /* Do nothing ... satisfy -- 2.39.5