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authorRaghava Aditya Renukunta <RaghavaAditya.Renukunta@microsemi.com>2016-04-25 23:31:26 -0700
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2016-06-07 17:21:57 -0700
commit4b7bac82604956ecda33c48bdbfb33ca37b7f632 (patch)
tree8202bb89e79a412ffff4749869fa4bf6d5ff1929 /drivers
parenta887008fdc3a094cce6f2f229ccbd6d83dbdc788 (diff)
downloadlwn-4b7bac82604956ecda33c48bdbfb33ca37b7f632.tar.gz
lwn-4b7bac82604956ecda33c48bdbfb33ca37b7f632.zip
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>
Diffstat (limited to 'drivers')
-rw-r--r--drivers/scsi/aacraid/commsup.c8
1 files 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