From 669f044170d8933c3d66d231b69ea97cb8447338 Mon Sep 17 00:00:00 2001 From: Bart Van Assche Date: Tue, 22 Nov 2016 16:17:13 -0800 Subject: [PATCH] scsi: srp_transport: Move queuecommand() wait code to SCSI core Additionally, rename srp_wait_for_queuecommand() into scsi_wait_for_queuecommand() and add a comment about the queuecommand() call from scsi_send_eh_cmnd(). Note: this patch changes scsi_internal_device_block from a function that did not sleep into a function that may sleep. This is fine for all callers of this function: * scsi_internal_device_block() is called from the mpt3sas device while that driver holds the ioc->dm_cmds.mutex. This means that the mpt3sas driver calls this function from thread context. * scsi_target_block() is called by __iscsi_block_session() from kernel thread context and with IRQs enabled. * The SRP transport code also calls scsi_target_block() from kernel thread context while sleeping is allowed. * The snic driver also calls scsi_target_block() from a context from which sleeping is allowed. The scsi_target_block() call namely occurs immediately after a scsi_flush_work() call. [mkp: s/shost/sdev/] Signed-off-by: Bart Van Assche Reviewed-by: Sagi Grimberg Reviewed-by: Martin K. Petersen Cc: James Bottomley Cc: Christoph Hellwig Cc: Doug Ledford Signed-off-by: Martin K. Petersen --- drivers/scsi/scsi_lib.c | 41 +++++++++++++++++++++++++++++-- drivers/scsi/scsi_transport_srp.c | 41 +++++-------------------------- 2 files changed, 45 insertions(+), 37 deletions(-) diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c index f23ec240cab0..0f81add6025e 100644 --- a/drivers/scsi/scsi_lib.c +++ b/drivers/scsi/scsi_lib.c @@ -2733,6 +2733,39 @@ void sdev_evt_send_simple(struct scsi_device *sdev, } EXPORT_SYMBOL_GPL(sdev_evt_send_simple); +/** + * scsi_request_fn_active() - number of kernel threads inside scsi_request_fn() + * @sdev: SCSI device to count the number of scsi_request_fn() callers for. + */ +static int scsi_request_fn_active(struct scsi_device *sdev) +{ + struct request_queue *q = sdev->request_queue; + int request_fn_active; + + WARN_ON_ONCE(sdev->host->use_blk_mq); + + spin_lock_irq(q->queue_lock); + request_fn_active = q->request_fn_active; + spin_unlock_irq(q->queue_lock); + + return request_fn_active; +} + +/** + * scsi_wait_for_queuecommand() - wait for ongoing queuecommand() calls + * @sdev: SCSI device pointer. + * + * Wait until the ongoing shost->hostt->queuecommand() calls that are + * invoked from scsi_request_fn() have finished. + */ +static void scsi_wait_for_queuecommand(struct scsi_device *sdev) +{ + WARN_ON_ONCE(sdev->host->use_blk_mq); + + while (scsi_request_fn_active(sdev)) + msleep(20); +} + /** * scsi_device_quiesce - Block user issued commands. * @sdev: scsi device to quiesce. @@ -2817,8 +2850,7 @@ EXPORT_SYMBOL(scsi_target_resume); * @sdev: device to block * * Block request made by scsi lld's to temporarily stop all - * scsi commands on the specified device. Called from interrupt - * or normal process context. + * scsi commands on the specified device. May sleep. * * Returns zero if successful or error if not * @@ -2827,6 +2859,10 @@ EXPORT_SYMBOL(scsi_target_resume); * (which must be a legal transition). When the device is in this * state, all commands are deferred until the scsi lld reenables * the device with scsi_device_unblock or device_block_tmo fires. + * + * To do: avoid that scsi_send_eh_cmnd() calls queuecommand() after + * scsi_internal_device_block() has blocked a SCSI device and also + * remove the rport mutex lock and unlock calls from srp_queuecommand(). */ int scsi_internal_device_block(struct scsi_device *sdev) @@ -2854,6 +2890,7 @@ scsi_internal_device_block(struct scsi_device *sdev) spin_lock_irqsave(q->queue_lock, flags); blk_stop_queue(q); spin_unlock_irqrestore(q->queue_lock, flags); + scsi_wait_for_queuecommand(sdev); } return 0; diff --git a/drivers/scsi/scsi_transport_srp.c b/drivers/scsi/scsi_transport_srp.c index 02cfc6b1ee5a..b87a78673f65 100644 --- a/drivers/scsi/scsi_transport_srp.c +++ b/drivers/scsi/scsi_transport_srp.c @@ -24,7 +24,6 @@ #include #include #include -#include #include #include @@ -393,36 +392,6 @@ static void srp_reconnect_work(struct work_struct *work) } } -/** - * scsi_request_fn_active() - number of kernel threads inside scsi_request_fn() - * @shost: SCSI host for which to count the number of scsi_request_fn() callers. - * - * To do: add support for scsi-mq in this function. - */ -static int scsi_request_fn_active(struct Scsi_Host *shost) -{ - struct scsi_device *sdev; - struct request_queue *q; - int request_fn_active = 0; - - shost_for_each_device(sdev, shost) { - q = sdev->request_queue; - - spin_lock_irq(q->queue_lock); - request_fn_active += q->request_fn_active; - spin_unlock_irq(q->queue_lock); - } - - return request_fn_active; -} - -/* Wait until ongoing shost->hostt->queuecommand() calls have finished. */ -static void srp_wait_for_queuecommand(struct Scsi_Host *shost) -{ - while (scsi_request_fn_active(shost)) - msleep(20); -} - static void __rport_fail_io_fast(struct srp_rport *rport) { struct Scsi_Host *shost = rport_to_shost(rport); @@ -432,14 +401,17 @@ static void __rport_fail_io_fast(struct srp_rport *rport) if (srp_rport_set_state(rport, SRP_RPORT_FAIL_FAST)) return; + /* + * Call scsi_target_block() to wait for ongoing shost->queuecommand() + * calls before invoking i->f->terminate_rport_io(). + */ + scsi_target_block(rport->dev.parent); scsi_target_unblock(rport->dev.parent, SDEV_TRANSPORT_OFFLINE); /* Involve the LLD if possible to terminate all I/O on the rport. */ i = to_srp_internal(shost->transportt); - if (i->f->terminate_rport_io) { - srp_wait_for_queuecommand(shost); + if (i->f->terminate_rport_io) i->f->terminate_rport_io(rport); - } } /** @@ -567,7 +539,6 @@ int srp_reconnect_rport(struct srp_rport *rport) if (res) goto out; scsi_target_block(&shost->shost_gendev); - srp_wait_for_queuecommand(shost); res = rport->state != SRP_RPORT_LOST ? i->f->reconnect(rport) : -ENODEV; pr_debug("%s (state %d): transport.reconnect() returned %d\n", dev_name(&shost->shost_gendev), rport->state, res); -- 2.20.1