Hi This fixes a possible race in scsi_dh_emc. It is untested because I don't have the hardware. It could happen when we reload a multipath device and path failure happens at the same time.
This is a theoretical race condition (there are no reports of it hapenning), but a different bug was already triggered under the same conditions in QA testing. Mikulas --- scsi-dh-emc: fix activate vs set_params race The activate routine may be called concurrently with the set_params routine. This can happen when dm-multipath device is reloaded. When we reload a device mapper device, the new target instance is being created (that could call the set_params method) while the old target instance is still active (that could call the activate method). The activate and set_params routine share the same data and sense buffer, so it could result in incorrect behaviour if they are called concurrently. This patch adds a mutex to fix the race. Signed-off-by: Mikulas Patocka <[email protected]> --- drivers/scsi/device_handler/scsi_dh_emc.c | 11 +++++++++++ 1 file changed, 11 insertions(+) Index: linux-3.9-rc5-fast/drivers/scsi/device_handler/scsi_dh_emc.c =================================================================== --- linux-3.9-rc5-fast.orig/drivers/scsi/device_handler/scsi_dh_emc.c 2013-04-03 01:32:16.000000000 +0200 +++ linux-3.9-rc5-fast/drivers/scsi/device_handler/scsi_dh_emc.c 2013-04-03 01:45:13.000000000 +0200 @@ -111,6 +111,8 @@ struct clariion_dh_data { * path's mapped LUN */ int current_sp; + + struct mutex mtx; }; static inline struct clariion_dh_data @@ -536,6 +538,8 @@ static int clariion_activate(struct scsi struct clariion_dh_data *csdev = get_clariion_data(sdev); int result; + mutex_lock(&csdev->mtx); + result = clariion_send_inquiry(sdev, csdev); if (result != SCSI_DH_OK) goto done; @@ -562,6 +566,8 @@ done: csdev->port, lun_state[csdev->lun_state], csdev->default_sp + 'A'); + mutex_unlock(&csdev->mtx); + if (fn) fn(data, result); return 0; @@ -602,6 +608,8 @@ static int clariion_set_params(struct sc else csdev->flags &= ~CLARIION_HONOR_RESERVATIONS; + mutex_lock(&csdev->mtx); + /* * If this path is owned, we have to send a trespass command * with the new parameters. If not, simply return. Next trespass @@ -618,6 +626,8 @@ static int clariion_set_params(struct sc /* Update status */ result = clariion_send_inquiry(sdev, csdev); + mutex_unlock(&csdev->mtx); + done: return result; } @@ -683,6 +693,7 @@ static int clariion_bus_attach(struct sc h->lun_state = CLARIION_LUN_UNINITIALIZED; h->default_sp = CLARIION_UNBOUND_LU; h->current_sp = CLARIION_UNBOUND_LU; + mutex_init(&h->mtx); err = clariion_std_inquiry(sdev, h); if (err != SCSI_DH_OK) -- To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
