On Wed, Jul 18, 2018 at 7:38 PM, Bart Van Assche <bart.vanass...@wdc.com> wrote: > On Wed, 2018-07-18 at 01:22 -0400, Sreekanth Reddy wrote: >> In mpt3sas_base_clear_st() function smid value is reseted in wrong line, >> i.e. driver should reset smid value to zero after decrementing chain_offset >> counter in chain_lookup table but in current code, driver is resetting smid >> value before decrementing the chain_offset counter. which we are correcting >> with this patch. >> >> Signed-off-by: Sreekanth Reddy <sreekanth.re...@broadcom.com> >> --- >> drivers/scsi/mpt3sas/mpt3sas_base.c | 2 +- >> 1 file changed, 1 insertion(+), 1 deletion(-) >> >> diff --git a/drivers/scsi/mpt3sas/mpt3sas_base.c >> b/drivers/scsi/mpt3sas/mpt3sas_base.c >> index 902610d..94b939b 100644 >> --- a/drivers/scsi/mpt3sas/mpt3sas_base.c >> +++ b/drivers/scsi/mpt3sas/mpt3sas_base.c >> @@ -3283,8 +3283,8 @@ void mpt3sas_base_clear_st(struct MPT3SAS_ADAPTER *ioc, >> return; >> st->cb_idx = 0xFF; >> st->direct_io = 0; >> - st->smid = 0; >> atomic_set(&ioc->chain_lookup[st->smid - 1].chain_offset, 0); >> + st->smid = 0; >> } > > How can this patch be correct without memory barrier between the atomic set > and the > st->smid assignment?
Yes I agree that I need to add memory barrier around atomic_set() API. I was not aware of this before. Is it fine to use smp_mb__before_atomic() API before atomic_set() & smp_mb__after_atomic() API after atomic_set? Also in other places in driver, we are using atomic_inc() & atomic_dec() APIs without memory barrier, I need to add memory barrier their too. So is it fine to post separate patch for adding memory barrier around atomic_xyz() APIs? if yes then please consider this patch and I will post separate patch for adding memory barriers around the atomic_xyz() APIs. Thanks, Sreekanth > > Bart. > >
