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Petersen (Oracle)" , Sasha Levin Subject: [PATCH 7.1 176/228] scsi: core: pair EH runtime PM get and put Date: Thu, 20 Aug 2026 16:55:18 +0200 Message-ID: <20260820145250.038111857@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260820145244.450574346@linuxfoundation.org> References: <20260820145244.450574346@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 7.1-stable review patch. If anyone has any objections, please let me know. ------------------ From: Hongjie Fang [ Upstream commit 872f486259ae0bc6b73ca4735a15d013241f73e9 ] shost->eh_noresume is currently consulted twice in one error handling iteration: once before scsi_autopm_get_host() and once again before scsi_autopm_put_host(). That is racy when a PM-triggered error path flips shost->eh_noresume while the SCSI EH thread is still running. The problem flow looks like this: PM path ufshcd_set_dev_pwr_mode() shost->eh_noresume = 1 ufshcd_execute_start_stop <-- trigger EH ... shost->eh_noresume = 0 EH path scsi_error_handler() if (!shost->eh_noresume) scsi_autopm_get_host() <-- skipped ... if (!shost->eh_noresume) scsi_autopm_put_host() <-- executed later In that case one EH iteration can skip autoresume on entry and still drop a runtime PM reference on exit. That leaves an unmatched runtime PM put and can trigger a runtime PM usage count underflow. Fix this by making eh_noresume a regular bool so it can be accessed with READ_ONCE() and WRITE_ONCE(). Snapshot it once per EH iteration and use that snapshot for both runtime PM get and put decisions. Fixes: ae0751ffc77e ("[SCSI] add flag to skip the runtime PM calls on the host") Signed-off-by: Hongjie Fang Reviewed-by: Bart Van Assche Reviewed-by: Peter Wang Link: https://patch.msgid.link/20260729111614.2407559-1-hongjiefang@asrmicro.com Signed-off-by: Martin K. Petersen (Oracle) Signed-off-by: Sasha Levin --- drivers/scsi/scsi_error.c | 6 ++++-- drivers/ufs/core/ufshcd.c | 4 ++-- include/scsi/scsi_host.h | 6 +++--- 3 files changed, 9 insertions(+), 7 deletions(-) diff --git a/drivers/scsi/scsi_error.c b/drivers/scsi/scsi_error.c index 453a2232452db..74b70801269bd 100644 --- a/drivers/scsi/scsi_error.c +++ b/drivers/scsi/scsi_error.c @@ -2362,6 +2362,7 @@ static void scsi_unjam_host(struct Scsi_Host *shost) int scsi_error_handler(void *data) { struct Scsi_Host *shost = data; + bool eh_noresume; /* * We use TASK_INTERRUPTIBLE so that the thread is not @@ -2403,7 +2404,8 @@ int scsi_error_handler(void *data) * what we need to do to get it up and online again (if we can). * If we fail, we end up taking the thing offline. */ - if (!shost->eh_noresume && scsi_autopm_get_host(shost) != 0) { + eh_noresume = READ_ONCE(shost->eh_noresume); + if (!eh_noresume && scsi_autopm_get_host(shost) != 0) { SCSI_LOG_ERROR_RECOVERY(1, shost_printk(KERN_ERR, shost, "scsi_eh_%d: unable to autoresume\n", @@ -2427,7 +2429,7 @@ int scsi_error_handler(void *data) * which are still online. */ scsi_restart_operations(shost); - if (!shost->eh_noresume) + if (!eh_noresume) scsi_autopm_put_host(shost); } __set_current_state(TASK_RUNNING); diff --git a/drivers/ufs/core/ufshcd.c b/drivers/ufs/core/ufshcd.c index d6444b3c2ef16..4abeb77c3a0fa 100644 --- a/drivers/ufs/core/ufshcd.c +++ b/drivers/ufs/core/ufshcd.c @@ -9985,7 +9985,7 @@ static int ufshcd_set_dev_pwr_mode(struct ufs_hba *hba, * we are functional while we are here, skip host resume in error * handling context. */ - hba->host->eh_noresume = 1; + WRITE_ONCE(hba->host->eh_noresume, 1); /* * Current function would be generally called from the power management @@ -10007,7 +10007,7 @@ static int ufshcd_set_dev_pwr_mode(struct ufs_hba *hba, } scsi_device_put(sdp); - hba->host->eh_noresume = 0; + WRITE_ONCE(hba->host->eh_noresume, 0); return ret; } diff --git a/include/scsi/scsi_host.h b/include/scsi/scsi_host.h index f6b286fa59f21..98b0ccf0813ea 100644 --- a/include/scsi/scsi_host.h +++ b/include/scsi/scsi_host.h @@ -664,6 +664,9 @@ struct Scsi_Host { /* Asynchronous scan in progress */ bool async_scan __guarded_by(&scan_mutex); + /* Don't resume host in EH */ + bool eh_noresume; + unsigned active_mode:2; /* @@ -682,9 +685,6 @@ struct Scsi_Host { /* Task mgmt function in progress */ unsigned tmf_in_progress:1; - /* Don't resume host in EH */ - unsigned eh_noresume:1; - /* The controller does not support WRITE SAME */ unsigned no_write_same:1; -- 2.53.0