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scsi: mpt3sas: fix memory ordering on 64bit writes 

With commit 09c2f95ad4 ("scsi: mpt3sas: Swap I/O memory read value back
to cpu endianness"), 64bit writes in _base_writeq() were rewritten to use
__raw_writeq() instad of writeq().

This introduced a bug apparent on powerpc64 systems such as the Raptor
Talos II that causes the HBA to drop from the PCIe bus under heavy load and
being reinitialized after a couple of seconds.

It can easily be triggered on affacted systems by using something like

  fio --name=random-write --iodepth=4 --rw=randwrite --bs=4k --direct=0 \
    --size=128M --numjobs=64 --end_fsync=1
  fio --name=random-write --iodepth=4 --rw=randwrite --bs=64k --direct=0 \
    --size=128M --numjobs=64 --end_fsync=1

a couple of times. In my case I tested it on both a ZFS raidz2 and a btrfs
raid6 using LSI 9300-8i and 9400-8i controllers.

The fix consists in resembling the write ordering of writeq() by adding a
mandatory write memory barrier before device access and a compiler barrier
afterwards. The additional MMIO barrier is superfluous.

Signed-off-by: Stephan Günther <moepi@moepi.net>
Reported-by: Matt Corallo <linux@bluematt.me>
Acked-by: Sreekanth Reddy <Sreekanth.Reddy@broadcom.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
This commit is contained in:
Stephan Günther 2018-12-16 13:08:21 +01:00 committed by Martin K. Petersen
parent 17b18eaa6f
commit 23c3828aa2
1 changed files with 2 additions and 1 deletions
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3
drivers/scsi/mpt3sas/mpt3sas_base.c
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@ -3345,8 +3345,9 @@ _base_mpi_ep_writeq(__u64 b, volatile void __iomem *addr,
static inline void
_base_writeq(__u64 b, volatile void __iomem *addr, spinlock_t *writeq_lock)
{
wmb();
__raw_writeq(b, addr);
mmiowb();
barrier();
}
#else
static inline void