[PATCH 01/36] scsi: core: Prepare for enabling lock context analysis

[Bart Van Assche <bvanassche@acm.org>]

Document which functions expect that shost->scan_mutex is held. Inform
the compiler about synchronization object aliases with __assume_ctx_lock().

Signed-off-by: Bart Van Assche <bvanassche@acm.org>
---
 drivers/scsi/scsi_scan.c | 12 ++++++++++++
 include/scsi/scsi_host.h |  2 ++
 2 files changed, 14 insertions(+)

diff --git a/drivers/scsi/scsi_scan.c b/drivers/scsi/scsi_scan.c
index efcaf85ff699..738822d547f3 100644
--- a/drivers/scsi/scsi_scan.c
+++ b/drivers/scsi/scsi_scan.c
@@ -1185,6 +1185,7 @@ static int scsi_probe_and_add_lun(struct scsi_target *starget,
 				  struct scsi_device **sdevp,
 				  enum scsi_scan_mode rescan,
 				  void *hostdata)
+	__must_hold(&dev_to_shost(starget->dev.parent)->scan_mutex)
 {
 	struct scsi_device *sdev;
 	unsigned char *result;
@@ -1341,6 +1342,7 @@ static int scsi_probe_and_add_lun(struct scsi_target *starget,
 static void scsi_sequential_lun_scan(struct scsi_target *starget,
 				     blist_flags_t bflags, int scsi_level,
 				     enum scsi_scan_mode rescan)
+	__must_hold(&dev_to_shost(starget->dev.parent)->scan_mutex)
 {
 	uint max_dev_lun;
 	u64 sparse_lun, lun;
@@ -1432,6 +1434,7 @@ static void scsi_sequential_lun_scan(struct scsi_target *starget,
  **/
 static int scsi_report_lun_scan(struct scsi_target *starget, blist_flags_t bflags,
 				enum scsi_scan_mode rescan)
+	__must_hold(&dev_to_shost(starget->dev.parent)->scan_mutex)
 {
 	unsigned char scsi_cmd[MAX_COMMAND_SIZE];
 	unsigned int length;
@@ -1629,6 +1632,8 @@ struct scsi_device *__scsi_add_device(struct Scsi_Host *shost, uint channel,
 	scsi_autopm_get_target(starget);
 
 	mutex_lock(&shost->scan_mutex);
+	/* Tell the compiler that dev_to_shost(...) == shost. */
+	__assume_ctx_lock(&dev_to_shost(starget->dev.parent)->scan_mutex);
 	if (!shost->async_scan)
 		scsi_complete_async_scans();
 
@@ -1757,6 +1762,7 @@ EXPORT_SYMBOL(scsi_rescan_device);
 
 static void __scsi_scan_target(struct device *parent, unsigned int channel,
 		unsigned int id, u64 lun, enum scsi_scan_mode rescan)
+	__must_hold(&dev_to_shost(parent)->scan_mutex)
 {
 	struct Scsi_Host *shost = dev_to_shost(parent);
 	blist_flags_t bflags = 0;
@@ -1772,6 +1778,8 @@ static void __scsi_scan_target(struct device *parent, unsigned int channel,
 	starget = scsi_alloc_target(parent, channel, id);
 	if (!starget)
 		return;
+	/* Tell the compiler that dev_to_shost(...) == shost. */
+	__assume_ctx_lock(&dev_to_shost(starget->dev.parent)->scan_mutex);
 	scsi_autopm_get_target(starget);
 
 	if (lun != SCAN_WILD_CARD) {
@@ -1853,9 +1861,13 @@ EXPORT_SYMBOL(scsi_scan_target);
 static void scsi_scan_channel(struct Scsi_Host *shost, unsigned int channel,
 			      unsigned int id, u64 lun,
 			      enum scsi_scan_mode rescan)
+	__must_hold(&shost->scan_mutex)
 {
 	uint order_id;
 
+	/* Tell the compiler that dev_to_shost(...) == shost. */
+	__assume_ctx_lock(&dev_to_shost(&shost->shost_gendev)->scan_mutex);
+
 	if (id == SCAN_WILD_CARD)
 		for (id = 0; id < shost->max_id; ++id) {
 			/*
diff --git a/include/scsi/scsi_host.h b/include/scsi/scsi_host.h
index 7e2011830ba4..2bbe7cb0060b 100644
--- a/include/scsi/scsi_host.h
+++ b/include/scsi/scsi_host.h
@@ -534,6 +534,8 @@ struct scsi_host_template {
 		enum scsi_qc_status rc;					\
 									\
 		spin_lock_irqsave(shost->host_lock, irq_flags);		\
+		/* Tell the compiler that cmd->device->host == shost. */\
+		__assume_ctx_lock(cmd->device->host->host_lock);	\
 		rc = func_name##_lck(cmd);				\
 		spin_unlock_irqrestore(shost->host_lock, irq_flags);	\
 		return rc;						\