Messages in this thread | | | Date | Mon, 01 Dec 2008 20:52:50 +0100 | From | Stefan Richter <> | Subject | Re: [PATCH] ieee1394: sbp2: fix race condition in state change |
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I wrote: > An intermediate transition from _RUNNING to _IN_SHUTDOWN could have been > missed by the former code. > > Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de> > --- > drivers/ieee1394/sbp2.c | 9 +++++---- > 1 file changed, 5 insertions(+), 4 deletions(-) > > Index: linux/drivers/ieee1394/sbp2.c > =================================================================== > --- linux.orig/drivers/ieee1394/sbp2.c > +++ linux/drivers/ieee1394/sbp2.c > @@ -895,12 +895,13 @@ static void sbp2_host_reset(struct hpsb_ > return; > > read_lock_irqsave(&sbp2_hi_logical_units_lock, flags); > + > list_for_each_entry(lu, &hi->logical_units, lu_list) > - if (likely(atomic_read(&lu->state) != > - SBP2LU_STATE_IN_SHUTDOWN)) { > - atomic_set(&lu->state, SBP2LU_STATE_IN_RESET); > + if (atomic_cmpxchg(&lu->state, > + SBP2LU_STATE_RUNNING, SBP2LU_STATE_IN_RESET) > + == SBP2LU_STATE_RUNNING) > scsi_block_requests(lu->shost); > - } > + > read_unlock_irqrestore(&sbp2_hi_logical_units_lock, flags); > } >
Still not entirely correct. Maybe
scsi_block_requests(lu->shost); if (atomic_cmpxchg(&lu->state, SBP2LU_STATE_RUNNING, SBP2LU_STATE_IN_RESET) == SBP2LU_IN_SHUTDOWN) scsi_unblock_requests(lu->shost);
Does What I Mean. Or I should just put a lock around all lu->state and shost->host_self_blocked manipulations. -- Stefan Richter -=====-==--- ==-- ----= http://arcgraph.de/sr/
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