On Tue, 2015-10-06 at 12:08 -0700, Lee Duncan wrote: > Update the SCSI hosts module to use idr to manage > its host_no index instead of an ATOMIC integer. This > also allows using idr_find() to look up the SCSI > host structure given the host number. > > This means that the SCSI host number will now > be reclaimable. > > Signed-off-by: Lee Duncan <[email protected]> > Reviewed-by: Hannes Reinecke <[email protected]> > --- > drivers/scsi/hosts.c | 61 > ++++++++++++++++++++++++++-------------------------- > 1 file changed, 31 insertions(+), 30 deletions(- > > diff --git a/drivers/scsi/hosts.c b/drivers/scsi/hosts.c > index 8bb173e01084..afe7bd962ddb 100644 > --- a/drivers/scsi/hosts.c > +++ b/drivers/scsi/hosts.c [...] > + spin_lock(&host_index_lock); > + shost = idr_find(&host_index_idr, hostnum); > + spin_unlock(&host_index_lock); > + > + return shost ? scsi_host_get(shost) : NULL;
So the thing I don't like here is that there's a race between scsi_host_get() and the final put. What could happen is that idr_find() returns the host just before but scsi_host_dev_release() is executed before the return. In that instance, we'll reference freed memory in scsi_host_get() ... probably completely harmlessly, but it will show up occasionally on some of the traces ... particularly the ones doing a fuzz/stress test around host create/destroy. James -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
