From 0cd0e57ec858edda580fb90b53df5269216b61b2 Mon Sep 17 00:00:00 2001 From: George Spelvin Date: Fri, 3 Jul 2020 15:19:57 +0200 Subject: scsi: zfcp: Use prandom_u32_max() for backoff We don't need crypto-grade random numbers for randomized backoffs. Instead use prandom_u32_max(ep_ro) which generates a pseudo-random number uniformly distributed in the interval [0, ep_ro). Link: https://lore.kernel.org/r/8fc7c4c4069ff1783f4a9ccd84a923f581a09ec5.1593780621.git.bblock@linux.ibm.com Reviewed-by: Steffen Maier Signed-off-by: George Spelvin Signed-off-by: Benjamin Block Signed-off-by: Martin K. Petersen --- drivers/s390/scsi/zfcp_fc.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'drivers/s390') diff --git a/drivers/s390/scsi/zfcp_fc.c b/drivers/s390/scsi/zfcp_fc.c index b018b61bd168..d24cafe02708 100644 --- a/drivers/s390/scsi/zfcp_fc.c +++ b/drivers/s390/scsi/zfcp_fc.c @@ -48,7 +48,7 @@ unsigned int zfcp_fc_port_scan_backoff(void) { if (!port_scan_backoff) return 0; - return get_random_int() % port_scan_backoff; + return prandom_u32_max(port_scan_backoff); } static void zfcp_fc_port_scan_time(struct zfcp_adapter *adapter) -- cgit v1.2.3 From 459ad085d87b2468905fee231a77d961b5088e48 Mon Sep 17 00:00:00 2001 From: Julian Wiedmann Date: Fri, 3 Jul 2020 15:19:58 +0200 Subject: scsi: zfcp: Fix an outdated comment for zfcp_qdio_send() zfcp no longer uses the qdio PCI flag, update the comment. Link: https://lore.kernel.org/r/6717c26fc986bff8776d110e27c199b523684c63.1593780621.git.bblock@linux.ibm.com Fixes: 21ddaa53f92d ("[SCSI] zfcp: Remove PCI flag") Reviewed-by: Steffen Maier Reviewed-by: Fedor Loshakov Signed-off-by: Julian Wiedmann Signed-off-by: Benjamin Block Signed-off-by: Martin K. Petersen --- drivers/s390/scsi/zfcp_qdio.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'drivers/s390') diff --git a/drivers/s390/scsi/zfcp_qdio.c b/drivers/s390/scsi/zfcp_qdio.c index 3a7f3374d10a..d3d110a04884 100644 --- a/drivers/s390/scsi/zfcp_qdio.c +++ b/drivers/s390/scsi/zfcp_qdio.c @@ -246,7 +246,7 @@ int zfcp_qdio_sbal_get(struct zfcp_qdio *qdio) } /** - * zfcp_qdio_send - set PCI flag in first SBALE and send req to QDIO + * zfcp_qdio_send - send req to QDIO * @qdio: pointer to struct zfcp_qdio * @q_req: pointer to struct zfcp_qdio_req * Returns: 0 on success, error otherwise -- cgit v1.2.3 From b43cdb5ac856d9e004d31494c2c41fa36f67c00d Mon Sep 17 00:00:00 2001 From: Julian Wiedmann Date: Fri, 3 Jul 2020 15:20:01 +0200 Subject: scsi: zfcp: Clean up zfcp_erp_action_ready() We already maintain a pointer to act->adapter. Use it consistently to avoid any confusion about whose ->erp_ready_head and ->erp_ready_wq we are accessing. Link: https://lore.kernel.org/r/d1bb04322f240dee32f4c4a551bc93bc736f4b01.1593780621.git.bblock@linux.ibm.com Reviewed-by: Steffen Maier Signed-off-by: Julian Wiedmann Signed-off-by: Benjamin Block Signed-off-by: Martin K. Petersen --- drivers/s390/scsi/zfcp_erp.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'drivers/s390') diff --git a/drivers/s390/scsi/zfcp_erp.c b/drivers/s390/scsi/zfcp_erp.c index db320dab1fee..2011b021e9af 100644 --- a/drivers/s390/scsi/zfcp_erp.c +++ b/drivers/s390/scsi/zfcp_erp.c @@ -68,7 +68,7 @@ static void zfcp_erp_action_ready(struct zfcp_erp_action *act) { struct zfcp_adapter *adapter = act->adapter; - list_move(&act->list, &act->adapter->erp_ready_head); + list_move(&act->list, &adapter->erp_ready_head); zfcp_dbf_rec_run("erardy1", act); wake_up(&adapter->erp_ready_wq); zfcp_dbf_rec_run("erardy2", act); -- cgit v1.2.3 From 6bcb7c171a0ce0b0114aa088404e552b49d85576 Mon Sep 17 00:00:00 2001 From: Julian Wiedmann Date: Fri, 3 Jul 2020 15:20:02 +0200 Subject: scsi: zfcp: Replace open-coded list move Instead of manually moving each element of the unit and port lists into our temporary on-stack lists, splice them over in one go. Link: https://lore.kernel.org/r/cacb179f49ece50fd4dce119c61252d632cdc1d4.1593780621.git.bblock@linux.ibm.com Reviewed-by: Steffen Maier Signed-off-by: Julian Wiedmann Signed-off-by: Benjamin Block Signed-off-by: Martin K. Petersen --- drivers/s390/scsi/zfcp_ccw.c | 7 +++---- 1 file changed, 3 insertions(+), 4 deletions(-) (limited to 'drivers/s390') diff --git a/drivers/s390/scsi/zfcp_ccw.c b/drivers/s390/scsi/zfcp_ccw.c index 49eda141ea43..d9fd0a41da64 100644 --- a/drivers/s390/scsi/zfcp_ccw.c +++ b/drivers/s390/scsi/zfcp_ccw.c @@ -124,13 +124,12 @@ static void zfcp_ccw_remove(struct ccw_device *cdev) return; write_lock_irq(&adapter->port_list_lock); - list_for_each_entry_safe(port, p, &adapter->port_list, list) { + list_for_each_entry(port, &adapter->port_list, list) { write_lock(&port->unit_list_lock); - list_for_each_entry_safe(unit, u, &port->unit_list, list) - list_move(&unit->list, &unit_remove_lh); + list_splice_init(&port->unit_list, &unit_remove_lh); write_unlock(&port->unit_list_lock); - list_move(&port->list, &port_remove_lh); } + list_splice_init(&adapter->port_list, &port_remove_lh); write_unlock_irq(&adapter->port_list_lock); zfcp_ccw_adapter_put(adapter); /* put from zfcp_ccw_adapter_by_cdev */ -- cgit v1.2.3 From c3bfffa5ec6901f758160edfb046bdc56d89e8d2 Mon Sep 17 00:00:00 2001 From: Julian Wiedmann Date: Fri, 3 Jul 2020 15:20:03 +0200 Subject: scsi: zfcp: Avoid benign overflow of the Request Queue's free-level zfcp_qdio_send() and zfcp_qdio_int_req() run concurrently, adding and completing SBALs on the Request Queue. There's a theoretical race where zfcp_qdio_int_req() completes a number of SBALs & increments the queue's free-level _before_ zfcp_qdio_send() was able to decrement it. This can cause ->req_q_free to momentarily hold a value larger than QDIO_MAX_BUFFERS_PER_Q. Luckily zfcp_qdio_send() is always called under ->req_q_lock, and all readers of the free-level also take this lock. So we can trust that zfcp_qdio_send() will clean up such a temporary overflow before anyone can actually observe it. But it's still confusing and annoying to worry about. So adjust the code to avoid this race. Link: https://lore.kernel.org/r/7f61f59a1f8db270312e64644f9173b8f1ac895f.1593780621.git.bblock@linux.ibm.com Reviewed-by: Steffen Maier Signed-off-by: Julian Wiedmann Signed-off-by: Benjamin Block Signed-off-by: Martin K. Petersen --- drivers/s390/scsi/zfcp_qdio.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) (limited to 'drivers/s390') diff --git a/drivers/s390/scsi/zfcp_qdio.c b/drivers/s390/scsi/zfcp_qdio.c index d3d110a04884..e78d65bd46b1 100644 --- a/drivers/s390/scsi/zfcp_qdio.c +++ b/drivers/s390/scsi/zfcp_qdio.c @@ -260,17 +260,20 @@ int zfcp_qdio_send(struct zfcp_qdio *qdio, struct zfcp_qdio_req *q_req) zfcp_qdio_account(qdio); spin_unlock(&qdio->stat_lock); + atomic_sub(sbal_number, &qdio->req_q_free); + retval = do_QDIO(qdio->adapter->ccw_device, QDIO_FLAG_SYNC_OUTPUT, 0, q_req->sbal_first, sbal_number); if (unlikely(retval)) { + /* Failed to submit the IO, roll back our modifications. */ + atomic_add(sbal_number, &qdio->req_q_free); zfcp_qdio_zero_sbals(qdio->req_q, q_req->sbal_first, sbal_number); return retval; } /* account for transferred buffers */ - atomic_sub(sbal_number, &qdio->req_q_free); qdio->req_q_idx += sbal_number; qdio->req_q_idx %= QDIO_MAX_BUFFERS_PER_Q; -- cgit v1.2.3