4.20-stable review patch. If anyone has any objections, please let me know.
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[ Upstream commit 23c3828aa2f84edec7020c7397a22931e7a879e1 ]
With commit 09c2f95ad404 ("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 Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/scsi/mpt3sas/mpt3sas_base.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/drivers/scsi/mpt3sas/mpt3sas_base.c b/drivers/scsi/mpt3sas/mpt3sas_base.c index 2500377d0723..bfd826deabbe 100644 --- a/drivers/scsi/mpt3sas/mpt3sas_base.c +++ b/drivers/scsi/mpt3sas/mpt3sas_base.c @@ -3319,8 +3319,9 @@ _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