From: Qi Liu <liuqi115@xxxxxxxxxx> [ Upstream commit 16775db613c2bdea09705dcb876942c0641a1098 ] If we issue a controller reset command during executing a FLR a hung task may be found: Call trace: __switch_to+0x158/0x1cc __schedule+0x2e8/0x85c schedule+0x7c/0x110 schedule_timeout+0x190/0x1cc __down+0x7c/0xd4 down+0x5c/0x7c hisi_sas_task_exec+0x510/0x680 [hisi_sas_main] hisi_sas_queue_command+0x24/0x30 [hisi_sas_main] smp_execute_task_sg+0xf4/0x23c [libsas] sas_smp_phy_control+0x110/0x1e0 [libsas] transport_sas_phy_reset+0xc8/0x190 [libsas] phy_reset_work+0x2c/0x40 [libsas] process_one_work+0x1dc/0x48c worker_thread+0x15c/0x464 kthread+0x160/0x170 ret_from_fork+0x10/0x18 This is a race condition which occurs when the FLR completes first. Here the host HISI_SAS_RESETTING_BIT flag out gets of sync as HISI_SAS_RESETTING_BIT is not always cleared with the hisi_hba.sem held, so now only set/unset HISI_SAS_RESETTING_BIT under hisi_hba.sem . Link: https://lore.kernel.org/r/1639579061-179473-7-git-send-email-john.garry@xxxxxxxxxx Signed-off-by: Qi Liu <liuqi115@xxxxxxxxxx> Signed-off-by: John Garry <john.garry@xxxxxxxxxx> Signed-off-by: Martin K. Petersen <martin.petersen@xxxxxxxxxx> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> --- drivers/scsi/hisi_sas/hisi_sas_main.c | 8 +++++--- drivers/scsi/hisi_sas/hisi_sas_v3_hw.c | 1 + 2 files changed, 6 insertions(+), 3 deletions(-) diff --git a/drivers/scsi/hisi_sas/hisi_sas_main.c b/drivers/scsi/hisi_sas/hisi_sas_main.c index f206c433de325..8a13bc08d6575 100644 --- a/drivers/scsi/hisi_sas/hisi_sas_main.c +++ b/drivers/scsi/hisi_sas/hisi_sas_main.c @@ -1581,7 +1581,6 @@ void hisi_sas_controller_reset_prepare(struct hisi_hba *hisi_hba) { struct Scsi_Host *shost = hisi_hba->shost; - down(&hisi_hba->sem); hisi_hba->phy_state = hisi_hba->hw->get_phys_state(hisi_hba); scsi_block_requests(shost); @@ -1606,9 +1605,9 @@ void hisi_sas_controller_reset_done(struct hisi_hba *hisi_hba) if (hisi_hba->reject_stp_links_msk) hisi_sas_terminate_stp_reject(hisi_hba); hisi_sas_reset_init_all_devices(hisi_hba); - up(&hisi_hba->sem); scsi_unblock_requests(shost); clear_bit(HISI_SAS_RESETTING_BIT, &hisi_hba->flags); + up(&hisi_hba->sem); hisi_sas_rescan_topology(hisi_hba, hisi_hba->phy_state); } @@ -1619,8 +1618,11 @@ static int hisi_sas_controller_prereset(struct hisi_hba *hisi_hba) if (!hisi_hba->hw->soft_reset) return -1; - if (test_and_set_bit(HISI_SAS_RESETTING_BIT, &hisi_hba->flags)) + down(&hisi_hba->sem); + if (test_and_set_bit(HISI_SAS_RESETTING_BIT, &hisi_hba->flags)) { + up(&hisi_hba->sem); return -1; + } if (hisi_sas_debugfs_enable && hisi_hba->debugfs_itct[0].itct) hisi_hba->hw->debugfs_snapshot_regs(hisi_hba); diff --git a/drivers/scsi/hisi_sas/hisi_sas_v3_hw.c b/drivers/scsi/hisi_sas/hisi_sas_v3_hw.c index 0ef6c21bf0811..11a44d9dd9b2d 100644 --- a/drivers/scsi/hisi_sas/hisi_sas_v3_hw.c +++ b/drivers/scsi/hisi_sas/hisi_sas_v3_hw.c @@ -4848,6 +4848,7 @@ static void hisi_sas_reset_prepare_v3_hw(struct pci_dev *pdev) int rc; dev_info(dev, "FLR prepare\n"); + down(&hisi_hba->sem); set_bit(HISI_SAS_RESETTING_BIT, &hisi_hba->flags); hisi_sas_controller_reset_prepare(hisi_hba); -- 2.34.1
