From: Stefan Weinhuber After setting the status of the cqr and releasing the lock for the block cqr queue, we call the cqr callback function, which will usually just trigger the dasd_block_tasklet. But when the tasklet is already running the cqr might be processed before we invoke the callback function. In rare cases the callback pointer may already be invalid by the time we want to call it, which will result in a panic. Solution: Call the callback function first and then release the lock. Signed-off-by: Stefan Weinhuber Signed-off-by: Martin Schwidefsky --- drivers/s390/block/dasd.c | 12 ++++++------ 1 file changed, 6 insertions(+), 6 deletions(-) Index: quilt-2.6/drivers/s390/block/dasd.c =================================================================== --- quilt-2.6.orig/drivers/s390/block/dasd.c +++ quilt-2.6/drivers/s390/block/dasd.c @@ -1149,12 +1149,14 @@ static void __dasd_device_process_final_ { struct list_head *l, *n; struct dasd_ccw_req *cqr; + struct dasd_block *block; list_for_each_safe(l, n, final_queue) { cqr = list_entry(l, struct dasd_ccw_req, devlist); list_del_init(&cqr->devlist); - if (cqr->block) - spin_lock_bh(&cqr->block->queue_lock); + block = cqr->block; + if (block) + spin_lock_bh(&block->queue_lock); switch (cqr->status) { case DASD_CQR_SUCCESS: cqr->status = DASD_CQR_DONE; @@ -1172,15 +1174,13 @@ static void __dasd_device_process_final_ cqr, cqr->status); BUG(); } - if (cqr->block) - spin_unlock_bh(&cqr->block->queue_lock); if (cqr->callback != NULL) (cqr->callback)(cqr, cqr->callback_data); + if (block) + spin_unlock_bh(&block->queue_lock); } } - - /* * Take a look at the first request on the ccw queue and check * if it reached its expire time. If so, terminate the IO. -- blue skies, Martin. "Reality continues to ruin my life." - Calvin. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/