From 44a24cb3731495336d77f3a955a7004997270dfd Mon Sep 17 00:00:00 2001 From: Christof Schmitt Date: Wed, 8 Sep 2010 14:39:57 +0200 Subject: [SCSI] zfcp: Change spin_lock_bh to spin_lock_irq to fix lockdep warning With the change to use the data on the SCSI device, iterating through all LUNs/scsi_devices takes the SCSI host_lock. This triggers warnings from the lock dependency checker: ========================================================= [ INFO: possible irq lock inversion dependency detected ] 2.6.34.1 #97 --------------------------------------------------------- chchp/3224 just changed the state of lock: (&(shost->host_lock)->rlock){-.-...}, at: [<00000000003a73f4>] __scsi_iterate_devices+0x38/0xbc but this lock took another, HARDIRQ-unsafe lock in the past: (&(&qdio->req_q_lock)->rlock){+.-...} and interrupts could create inverse lock ordering between them. other info that might help us debug this: [ 24.972394] 2 locks held by chchp/3224: #0: (&(sch->lock)->rlock){-.-...}, at: [<0000000000401efa>] do_IRQ+0xb2/0x1e4 #1: (&adapter->port_list_lock){.-....}, at: [<0000000000490302>] zfcp_erp_modify_adapter_status+0x9e/0x16c [...] ========================================================= [ INFO: possible irq lock inversion dependency detected ] 2.6.34.1 #98 --------------------------------------------------------- chchp/3235 just changed the state of lock: (&(shost->host_lock)->rlock){-.-...}, at: [<00000000003a73f4>] __scsi_iterate_devices+0x38/0xbc but this lock took another, HARDIRQ-unsafe lock in the past: (&(&qdio->stat_lock)->rlock){+.-...} and interrupts could create inverse lock ordering between them. other info that might help us debug this: 2 locks held by chchp/3235: #0: (&(sch->lock)->rlock){-.-...}, at: [<0000000000401efa>] do_IRQ+0xb2/0x1e4 #1: (&adapter->port_list_lock){.-.-..}, at: [<00000000004902f6>] zfcp_erp_modify_adapter_status+0x9e/0x16c [...] To stop this warning, change the request queue lock to disable irqs, not only softirq. The changes are required only outside of the critical "send fcp command" path. Reviewed-by: Swen Schillig Signed-off-by: Christof Schmitt Signed-off-by: James Bottomley --- drivers/s390/scsi/zfcp_qdio.c | 18 ++++++++++-------- 1 file changed, 10 insertions(+), 8 deletions(-) (limited to 'drivers/s390/scsi/zfcp_qdio.c') diff --git a/drivers/s390/scsi/zfcp_qdio.c b/drivers/s390/scsi/zfcp_qdio.c index b2635759721c..60e6e5714eb9 100644 --- a/drivers/s390/scsi/zfcp_qdio.c +++ b/drivers/s390/scsi/zfcp_qdio.c @@ -60,13 +60,11 @@ static inline void zfcp_qdio_account(struct zfcp_qdio *qdio) unsigned long long now, span; int used; - spin_lock(&qdio->stat_lock); now = get_clock_monotonic(); span = (now - qdio->req_q_time) >> 12; used = QDIO_MAX_BUFFERS_PER_Q - atomic_read(&qdio->req_q_free); qdio->req_q_util += used * span; qdio->req_q_time = now; - spin_unlock(&qdio->stat_lock); } static void zfcp_qdio_int_req(struct ccw_device *cdev, unsigned int qdio_err, @@ -84,7 +82,9 @@ static void zfcp_qdio_int_req(struct ccw_device *cdev, unsigned int qdio_err, /* cleanup all SBALs being program-owned now */ zfcp_qdio_zero_sbals(qdio->req_q, idx, count); + spin_lock_irq(&qdio->stat_lock); zfcp_qdio_account(qdio); + spin_unlock_irq(&qdio->stat_lock); atomic_add(count, &qdio->req_q_free); wake_up(&qdio->req_q_wq); } @@ -201,11 +201,11 @@ int zfcp_qdio_sbals_from_sg(struct zfcp_qdio *qdio, struct zfcp_qdio_req *q_req, static int zfcp_qdio_sbal_check(struct zfcp_qdio *qdio) { - spin_lock_bh(&qdio->req_q_lock); + spin_lock_irq(&qdio->req_q_lock); if (atomic_read(&qdio->req_q_free) || !(atomic_read(&qdio->adapter->status) & ZFCP_STATUS_ADAPTER_QDIOUP)) return 1; - spin_unlock_bh(&qdio->req_q_lock); + spin_unlock_irq(&qdio->req_q_lock); return 0; } @@ -223,7 +223,7 @@ int zfcp_qdio_sbal_get(struct zfcp_qdio *qdio) { long ret; - spin_unlock_bh(&qdio->req_q_lock); + spin_unlock_irq(&qdio->req_q_lock); ret = wait_event_interruptible_timeout(qdio->req_q_wq, zfcp_qdio_sbal_check(qdio), 5 * HZ); @@ -239,7 +239,7 @@ int zfcp_qdio_sbal_get(struct zfcp_qdio *qdio) zfcp_erp_adapter_reopen(qdio->adapter, 0, "qdsbg_1", NULL); } - spin_lock_bh(&qdio->req_q_lock); + spin_lock_irq(&qdio->req_q_lock); return -EIO; } @@ -254,7 +254,9 @@ int zfcp_qdio_send(struct zfcp_qdio *qdio, struct zfcp_qdio_req *q_req) int retval; u8 sbal_number = q_req->sbal_number; + spin_lock(&qdio->stat_lock); zfcp_qdio_account(qdio); + spin_unlock(&qdio->stat_lock); retval = do_QDIO(qdio->adapter->ccw_device, QDIO_FLAG_SYNC_OUTPUT, 0, q_req->sbal_first, sbal_number); @@ -328,9 +330,9 @@ void zfcp_qdio_close(struct zfcp_qdio *qdio) return; /* clear QDIOUP flag, thus do_QDIO is not called during qdio_shutdown */ - spin_lock_bh(&qdio->req_q_lock); + spin_lock_irq(&qdio->req_q_lock); atomic_clear_mask(ZFCP_STATUS_ADAPTER_QDIOUP, &adapter->status); - spin_unlock_bh(&qdio->req_q_lock); + spin_unlock_irq(&qdio->req_q_lock); wake_up(&qdio->req_q_wq); -- cgit v1.2.3