ata: libata: Document when host->eh_mutex should be held

Annotate the following functions with __must_hold(&host->eh_mutex):
 * All ata_port_operations.error_handler() implementations.
 * ata_eh_reset() and ata_eh_recover() because these functions call
   ata_eh_release() and ata_eh_acquire().
 * All callers of ata_eh_reset() and ata_eh_recover().

Enable Clang's context analysis. This will cause the build to fail if
e.g. a locking bug would be introduced in an error path. This patch
should not affect the generated assembler code.

Signed-off-by: Bart Van Assche <bvanassche@acm.org>
[cassel: drop note about clang 23 from commit log]
Signed-off-by: Niklas Cassel <cassel@kernel.org>

Author: bvanassche

drivers/ata/Makefile

@@ -1,5 +1,7 @@
 # SPDX-License-Identifier: GPL-2.0
 
+CONTEXT_ANALYSIS := y
+
 obj-$(CONFIG_ATA)		+= libata.o
 
 # non-SFF interface

drivers/ata/ahci.h

@@ -448,7 +448,8 @@ void ahci_set_em_messages(struct ahci_host_priv *hpriv,
 int ahci_reset_em(struct ata_host *host);
 void ahci_print_info(struct ata_host *host, const char *scc_s);
 int ahci_host_activate(struct ata_host *host, const struct scsi_host_template *sht);
-void ahci_error_handler(struct ata_port *ap);
+void ahci_error_handler(struct ata_port *ap)
+	__must_hold(&ap->host->eh_mutex);
 u32 ahci_handle_port_intr(struct ata_host *host, u32 irq_masked);
 
 static inline void __iomem *__ahci_port_base(struct ahci_host_priv *hpriv,

drivers/ata/ahci_imx.c

@@ -598,6 +598,7 @@ static void imx_sata_disable(struct ahci_host_priv *hpriv)
 }
 
 static void ahci_imx_error_handler(struct ata_port *ap)
+	__must_hold(&ap->host->eh_mutex)
 {
 	u32 reg_val;
 	struct ata_device *dev;

drivers/ata/libahci.c

@@ -2208,6 +2208,7 @@ static void ahci_thaw(struct ata_port *ap)
 }
 
 void ahci_error_handler(struct ata_port *ap)
+	__must_hold(&ap->host->eh_mutex)
 {
 	struct ahci_host_priv *hpriv = ap->host->private_data;
 

drivers/ata/libata-core.c

@@ -6835,6 +6835,7 @@ EXPORT_SYMBOL_GPL(ata_ratelimit);
  *	Might sleep.
  */
 void ata_msleep(struct ata_port *ap, unsigned int msecs)
+	__context_unsafe(conditional locking)
 {
 	bool owns_eh = ap && ap->host->eh_owner == current;
 
@@ -6909,6 +6910,7 @@ static unsigned int ata_dummy_qc_issue(struct ata_queued_cmd *qc)
 }
 
 static void ata_dummy_error_handler(struct ata_port *ap)
+	__must_hold(&ap->host->eh_mutex)
 {
 	/* truly dummy */
 }

drivers/ata/libata-eh.c

@@ -469,6 +469,7 @@ static void ata_eh_clear_action(struct ata_link *link, struct ata_device *dev,
  *	EH context.
  */
 void ata_eh_acquire(struct ata_port *ap)
+	__acquires(&ap->host->eh_mutex)
 {
 	mutex_lock(&ap->host->eh_mutex);
 	WARN_ON_ONCE(ap->host->eh_owner);
@@ -486,6 +487,7 @@ void ata_eh_acquire(struct ata_port *ap)
  *	EH context.
  */
 void ata_eh_release(struct ata_port *ap)
+	__releases(&ap->host->eh_mutex)
 {
 	WARN_ON_ONCE(ap->host->eh_owner != current);
 	ap->host->eh_owner = NULL;
@@ -2833,6 +2835,7 @@ static bool ata_eh_followup_srst_needed(struct ata_link *link, int rc)
 
 int ata_eh_reset(struct ata_port *ap, struct ata_link *link, int classify,
 		 struct ata_reset_operations *reset_ops)
+	__must_hold(&ap->host->eh_mutex)
 {
 	struct ata_link *slave = ap->slave_link;
 	struct ata_eh_context *ehc = &link->eh_context;
@@ -3815,6 +3818,7 @@ static int ata_eh_handle_dev_fail(struct ata_device *dev, int err)
  */
 int ata_eh_recover(struct ata_port *ap, struct ata_reset_operations *reset_ops,
 		   struct ata_link **r_failed_link)
+	__must_hold(&ap->host->eh_mutex)
 {
 	struct ata_link *link;
 	struct ata_device *dev;
@@ -4112,6 +4116,7 @@ void ata_eh_finish(struct ata_port *ap)
  *	Kernel thread context (may sleep).
  */
 void ata_std_error_handler(struct ata_port *ap)
+	__must_hold(&ap->host->eh_mutex)
 {
 	struct ata_reset_operations *reset_ops = &ap->ops->reset;
 	struct ata_link *link = &ap->link;

drivers/ata/libata-pmp.c

@@ -756,6 +756,7 @@ static int sata_pmp_revalidate_quick(struct ata_device *dev)
  */
 static int sata_pmp_eh_recover_pmp(struct ata_port *ap,
 				   struct ata_reset_operations *reset_ops)
+	__must_hold(&ap->host->eh_mutex)
 {
 	struct ata_link *link = &ap->link;
 	struct ata_eh_context *ehc = &link->eh_context;
@@ -921,6 +922,7 @@ static int sata_pmp_handle_link_fail(struct ata_link *link, int *link_tries)
  *	0 on success, -errno on failure.
  */
 static int sata_pmp_eh_recover(struct ata_port *ap)
+	__must_hold(&ap->host->eh_mutex)
 {
 	struct ata_port_operations *ops = ap->ops;
 	int pmp_tries, link_tries[SATA_PMP_MAX_PORTS];
@@ -1098,6 +1100,7 @@ static int sata_pmp_eh_recover(struct ata_port *ap)
  *	Kernel thread context (may sleep).
  */
 void sata_pmp_error_handler(struct ata_port *ap)
+	__must_hold(&ap->host->eh_mutex)
 {
 	ata_eh_autopsy(ap);
 	ata_eh_report(ap);

drivers/ata/libata-sff.c

@@ -2053,6 +2053,7 @@ EXPORT_SYMBOL_GPL(ata_sff_drain_fifo);
  *	Kernel thread context (may sleep)
  */
 void ata_sff_error_handler(struct ata_port *ap)
+	__must_hold(&ap->host->eh_mutex)
 {
 	struct ata_queued_cmd *qc;
 	unsigned long flags;
@@ -2769,6 +2770,7 @@ EXPORT_SYMBOL_GPL(ata_bmdma_interrupt);
  *	Kernel thread context (may sleep)
  */
 void ata_bmdma_error_handler(struct ata_port *ap)
+	__must_hold(&ap->host->eh_mutex)
 {
 	struct ata_queued_cmd *qc;
 	unsigned long flags;

drivers/ata/libata.h

@@ -173,8 +173,10 @@ void ata_scsi_requeue_deferred_qc(struct ata_port *ap);
 /* libata-eh.c */
 extern unsigned int ata_internal_cmd_timeout(struct ata_device *dev, u8 cmd);
 extern void ata_internal_cmd_timed_out(struct ata_device *dev, u8 cmd);
-extern void ata_eh_acquire(struct ata_port *ap);
-extern void ata_eh_release(struct ata_port *ap);
+extern void ata_eh_acquire(struct ata_port *ap)
+	__acquires(&ap->host->eh_mutex);
+extern void ata_eh_release(struct ata_port *ap)
+	__releases(&ap->host->eh_mutex);
 extern void ata_scsi_error(struct Scsi_Host *host);
 extern void ata_eh_fastdrain_timerfn(struct timer_list *t);
 extern void ata_qc_schedule_eh(struct ata_queued_cmd *qc);
@@ -188,10 +190,12 @@ extern void ata_eh_autopsy(struct ata_port *ap);
 const char *ata_get_cmd_name(u8 command);
 extern void ata_eh_report(struct ata_port *ap);
 extern int ata_eh_reset(struct ata_port *ap, struct ata_link *link,
-			int classify, struct ata_reset_operations *reset_ops);
+			int classify, struct ata_reset_operations *reset_ops)
+	__must_hold(&ap->host->eh_mutex);
 extern int ata_eh_recover(struct ata_port *ap,
 			  struct ata_reset_operations *reset_ops,
-			  struct ata_link **r_failed_disk);
+			  struct ata_link **r_failed_disk)
+	__must_hold(&ap->host->eh_mutex);
 extern void ata_eh_finish(struct ata_port *ap);
 extern int ata_ering_map(struct ata_ering *ering,
 			 int (*map_fn)(struct ata_ering_entry *, void *),

drivers/ata/pata_arasan_cf.c

@@ -658,6 +658,7 @@ static void arasan_cf_freeze(struct ata_port *ap)
 }
 
 static void arasan_cf_error_handler(struct ata_port *ap)
+	__must_hold(&ap->host->eh_mutex)
 {
 	struct arasan_cf_dev *acdev = ap->host->private_data;