The patch below does not apply to the 4.4-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
From 2c197870e4701610ec3b1143808d4e31152caf30 Mon Sep 17 00:00:00 2001
From: Julian Wiedmann jwi@linux.ibm.com Date: Mon, 31 May 2021 18:40:06 +0300 Subject: [PATCH] s390/qdio: fix roll-back after timeout on ESTABLISH ccw
When qdio_establish() times out while waiting for the ESTABLISH ccw to complete, it calls qdio_shutdown() to roll back all of its previous actions. But at this point the qdio_irq's state is still QDIO_IRQ_STATE_INACTIVE, so qdio_shutdown() will exit immediately without doing any actual work.
Which means that eg. the qdio_irq's thinint-indicator stays registered, and cdev->handler isn't restored to its old value. And since commit 954d6235be41 ("s390/qdio: make thinint registration symmetric") the qdio_irq also stays on the tiq_list, so on the next qdio_establish() we might get a helpful BUG from the list-debugging code:
... [ 4633.512591] list_add double add: new=00000000005a4110, prev=00000001b357db78, next=00000000005a4110. [ 4633.512621] ------------[ cut here ]------------ [ 4633.512623] kernel BUG at lib/list_debug.c:29! ... [ 4633.512796] [<00000001b2c6ee9a>] __list_add_valid+0x82/0xa0 [ 4633.512798] ([<00000001b2c6ee96>] __list_add_valid+0x7e/0xa0) [ 4633.512800] [<00000001b2fcecce>] qdio_establish_thinint+0x116/0x190 [ 4633.512805] [<00000001b2fcbe58>] qdio_establish+0x128/0x498 ...
Fix this by extracting a goto-chain from the existing error exits in qdio_establish(), and check the return value of the wait_event_...() to detect the timeout condition.
Fixes: 779e6e1c724d ("[S390] qdio: new qdio driver.") Root-caused-by: Benjamin Block bblock@linux.ibm.com Signed-off-by: Julian Wiedmann jwi@linux.ibm.com Reviewed-by: Benjamin Block bblock@linux.ibm.com Cc: stable@vger.kernel.org # 2.6.27 Signed-off-by: Heiko Carstens hca@linux.ibm.com
diff --git a/drivers/s390/cio/qdio_main.c b/drivers/s390/cio/qdio_main.c index 3052fab00597..32c8c46b19b6 100644 --- a/drivers/s390/cio/qdio_main.c +++ b/drivers/s390/cio/qdio_main.c @@ -1083,6 +1083,7 @@ int qdio_establish(struct ccw_device *cdev, { struct qdio_irq *irq_ptr = cdev->private->qdio_data; struct subchannel_id schid; + long timeout; int rc;
ccw_device_get_schid(cdev, &schid); @@ -1111,11 +1112,8 @@ int qdio_establish(struct ccw_device *cdev, qdio_setup_irq(irq_ptr, init_data);
rc = qdio_establish_thinint(irq_ptr); - if (rc) { - qdio_shutdown_irq(irq_ptr); - mutex_unlock(&irq_ptr->setup_mutex); - return rc; - } + if (rc) + goto err_thinint;
/* establish q */ irq_ptr->ccw.cmd_code = irq_ptr->equeue.cmd; @@ -1131,15 +1129,16 @@ int qdio_establish(struct ccw_device *cdev, if (rc) { DBF_ERROR("%4x est IO ERR", irq_ptr->schid.sch_no); DBF_ERROR("rc:%4x", rc); - qdio_shutdown_thinint(irq_ptr); - qdio_shutdown_irq(irq_ptr); - mutex_unlock(&irq_ptr->setup_mutex); - return rc; + goto err_ccw_start; }
- wait_event_interruptible_timeout(cdev->private->wait_q, - irq_ptr->state == QDIO_IRQ_STATE_ESTABLISHED || - irq_ptr->state == QDIO_IRQ_STATE_ERR, HZ); + timeout = wait_event_interruptible_timeout(cdev->private->wait_q, + irq_ptr->state == QDIO_IRQ_STATE_ESTABLISHED || + irq_ptr->state == QDIO_IRQ_STATE_ERR, HZ); + if (timeout <= 0) { + rc = (timeout == -ERESTARTSYS) ? -EINTR : -ETIME; + goto err_ccw_timeout; + }
if (irq_ptr->state != QDIO_IRQ_STATE_ESTABLISHED) { mutex_unlock(&irq_ptr->setup_mutex); @@ -1156,6 +1155,14 @@ int qdio_establish(struct ccw_device *cdev, qdio_print_subchannel_info(irq_ptr); qdio_setup_debug_entries(irq_ptr); return 0; + +err_ccw_timeout: +err_ccw_start: + qdio_shutdown_thinint(irq_ptr); +err_thinint: + qdio_shutdown_irq(irq_ptr); + mutex_unlock(&irq_ptr->setup_mutex); + return rc; } EXPORT_SYMBOL_GPL(qdio_establish);