From: Sreekanth Reddy sreekanth.reddy@broadcom.com
[ Upstream commit c2fe742ff6e77c5b4fe4ad273191ddf28fdea25e ]
During expander reset handling, the driver invokes kernel function scsi_host_find_tag() to obtain outstanding requests associated with the scsi host managed by the driver. Driver loops from tag value zero to hba queue depth to obtain the outstanding scmds. But when blk-mq is enabled, the block layer may return stale entry for one or more requests. This may lead to kernel panic if the returned value is inaccessible or the memory pointed by the returned value is reused.
Reference of upstream discussion:
https://patchwork.kernel.org/patch/10734933/
Instead of calling scsi_host_find_tag() API for each and every smid (smid is tag +1) from one to shost->can_queue, now driver will call this API (to obtain the outstanding scmd) only for those smid's which are outstanding at the driver level.
Driver will determine whether this smid is outstanding at driver level by looking into it's corresponding MPI request frame, if its MPI request frame is empty, then it means that this smid is free and does not need to call scsi_host_find_tag() for it. By doing this, driver will invoke scsi_host_find_tag() for only those tags which are outstanding at the driver level.
Driver will check whether particular MPI request frame is empty or not by looking into the "DevHandle" field. If this field is zero then it means that this MPI request is empty. For active MPI request DevHandle must be non-zero.
Also driver will memset the MPI request frame once the corresponding scmd is processed (i.e. just before calling scmd->done function).
Signed-off-by: Sreekanth Reddy sreekanth.reddy@broadcom.com Signed-off-by: Martin K. Petersen martin.petersen@oracle.com Signed-off-by: Sasha Levin (Microsoft) sashal@kernel.org --- drivers/scsi/mpt3sas/mpt3sas_base.c | 6 ++++++ drivers/scsi/mpt3sas/mpt3sas_scsih.c | 12 ++++++++++++ 2 files changed, 18 insertions(+)
diff --git a/drivers/scsi/mpt3sas/mpt3sas_base.c b/drivers/scsi/mpt3sas/mpt3sas_base.c index b59bba3e6516..8776330175e3 100644 --- a/drivers/scsi/mpt3sas/mpt3sas_base.c +++ b/drivers/scsi/mpt3sas/mpt3sas_base.c @@ -3280,12 +3280,18 @@ mpt3sas_base_free_smid(struct MPT3SAS_ADAPTER *ioc, u16 smid)
if (smid < ioc->hi_priority_smid) { struct scsiio_tracker *st; + void *request;
st = _get_st_from_smid(ioc, smid); if (!st) { _base_recovery_check(ioc); return; } + + /* Clear MPI request frame */ + request = mpt3sas_base_get_msg_frame(ioc, smid); + memset(request, 0, ioc->request_sz); + mpt3sas_base_clear_st(ioc, st); _base_recovery_check(ioc); return; diff --git a/drivers/scsi/mpt3sas/mpt3sas_scsih.c b/drivers/scsi/mpt3sas/mpt3sas_scsih.c index 622832e55211..73d661a0ecbb 100644 --- a/drivers/scsi/mpt3sas/mpt3sas_scsih.c +++ b/drivers/scsi/mpt3sas/mpt3sas_scsih.c @@ -1474,11 +1474,23 @@ mpt3sas_scsih_scsi_lookup_get(struct MPT3SAS_ADAPTER *ioc, u16 smid) { struct scsi_cmnd *scmd = NULL; struct scsiio_tracker *st; + Mpi25SCSIIORequest_t *mpi_request;
if (smid > 0 && smid <= ioc->scsiio_depth - INTERNAL_SCSIIO_CMDS_COUNT) { u32 unique_tag = smid - 1;
+ mpi_request = mpt3sas_base_get_msg_frame(ioc, smid); + + /* + * If SCSI IO request is outstanding at driver level then + * DevHandle filed must be non-zero. If DevHandle is zero + * then it means that this smid is free at driver level, + * so return NULL. + */ + if (!mpi_request->DevHandle) + return scmd; + scmd = scsi_host_find_tag(ioc->shost, unique_tag); if (scmd) { st = scsi_cmd_priv(scmd);