5.15-stable review patch. If anyone has any objections, please let me know.
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From: Bart Van Assche bvanassche@acm.org
[ Upstream commit a0b7780602b1b196f47e527fec82166a7e67c4d0 ]
Commit 995412e23bb2 ("blk-mq: Replace tags->lock with SRCU for tag iterators") introduced the following regression:
Call trace: __srcu_read_lock+0x30/0x80 (P) blk_mq_tagset_busy_iter+0x44/0x300 scsi_host_busy+0x38/0x70 ufshcd_print_host_state+0x34/0x1bc ufshcd_link_startup.constprop.0+0xe4/0x2e0 ufshcd_init+0x944/0xf80 ufshcd_pltfrm_init+0x504/0x820 ufs_rockchip_probe+0x2c/0x88 platform_probe+0x5c/0xa4 really_probe+0xc0/0x38c __driver_probe_device+0x7c/0x150 driver_probe_device+0x40/0x120 __driver_attach+0xc8/0x1e0 bus_for_each_dev+0x7c/0xdc driver_attach+0x24/0x30 bus_add_driver+0x110/0x230 driver_register+0x68/0x130 __platform_driver_register+0x20/0x2c ufs_rockchip_pltform_init+0x1c/0x28 do_one_initcall+0x60/0x1e0 kernel_init_freeable+0x248/0x2c4 kernel_init+0x20/0x140 ret_from_fork+0x10/0x20
Fix this regression by making scsi_host_busy() check whether the SCSI host tag set has already been initialized. tag_set->ops is set by scsi_mq_setup_tags() just before blk_mq_alloc_tag_set() is called. This fix is based on the assumption that scsi_host_busy() and scsi_mq_setup_tags() calls are serialized. This is the case in the UFS driver.
Reported-by: Sebastian Reichel sebastian.reichel@collabora.com Closes: https://lore.kernel.org/linux-block/pnezafputodmqlpumwfbn644ohjybouveehcjhz2... Cc: Ming Lei ming.lei@redhat.com Cc: Jens Axboe axboe@kernel.dk Signed-off-by: Bart Van Assche bvanassche@acm.org Reviewed-by: Ming Lei ming.lei@redhat.com Tested-by: Sebastian Reichel sebastian.reichel@collabora.com Link: https://patch.msgid.link/20251007214800.1678255-1-bvanassche@acm.org Signed-off-by: Martin K. Petersen martin.petersen@oracle.com Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/scsi/hosts.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-)
diff --git a/drivers/scsi/hosts.c b/drivers/scsi/hosts.c index eb3e8b41adb10..cf842c97639a7 100644 --- a/drivers/scsi/hosts.c +++ b/drivers/scsi/hosts.c @@ -594,8 +594,9 @@ int scsi_host_busy(struct Scsi_Host *shost) { int cnt = 0;
- blk_mq_tagset_busy_iter(&shost->tag_set, - scsi_host_check_in_flight, &cnt); + if (shost->tag_set.ops) + blk_mq_tagset_busy_iter(&shost->tag_set, + scsi_host_check_in_flight, &cnt); return cnt; } EXPORT_SYMBOL(scsi_host_busy);