1 files changed, 89 insertions, 85 deletions

diff --git a/fs/pstore/platform.c b/fs/pstore/platform.c
index d896457e7c11..0c034ea39954 100644
--- a/fs/pstore/platform.c
+++ b/fs/pstore/platform.c
@@ -44,7 +44,7 @@ static int pstore_update_ms = -1;
 module_param_named(update_ms, pstore_update_ms, int, 0600);
 MODULE_PARM_DESC(update_ms, "milliseconds before pstore updates its content "
 		 "(default is -1, which means runtime updates are disabled; "
-		 "enabling this option is not safe, it may lead to further "
+		 "enabling this option may not be safe; it may lead to further "
 		 "corruption on Oopses)");
 
 /* Names should be in the same order as the enum pstore_type_id */
@@ -69,19 +69,25 @@ static void pstore_dowork(struct work_struct *);
 static DECLARE_WORK(pstore_work, pstore_dowork);
 
 /*
- * pstore_lock just protects "psinfo" during
- * calls to pstore_register()
+ * psinfo_lock protects "psinfo" during calls to
+ * pstore_register(), pstore_unregister(), and
+ * the filesystem mount/unmount routines.
  */
-static DEFINE_SPINLOCK(pstore_lock);
+static DEFINE_MUTEX(psinfo_lock);
 struct pstore_info *psinfo;
 
 static char *backend;
+module_param(backend, charp, 0444);
+MODULE_PARM_DESC(backend, "specific backend to use");
+
 static char *compress =
 #ifdef CONFIG_PSTORE_COMPRESS_DEFAULT
 		CONFIG_PSTORE_COMPRESS_DEFAULT;
 #else
 		NULL;
 #endif
+module_param(compress, charp, 0444);
+MODULE_PARM_DESC(compress, "compression to use");
 
 /* Compression parameters */
 static struct crypto_comp *tfm;
@@ -95,7 +101,7 @@ static char *big_oops_buf;
 static size_t big_oops_buf_sz;
 
 /* How much of the console log to snapshot */
-unsigned long kmsg_bytes = PSTORE_DEFAULT_KMSG_BYTES;
+unsigned long kmsg_bytes = CONFIG_PSTORE_DEFAULT_KMSG_BYTES;
 
 void pstore_set_kmsg_bytes(int bytes)
 {
@@ -129,41 +135,30 @@ enum pstore_type_id pstore_name_to_type(const char *name)
 }
 EXPORT_SYMBOL_GPL(pstore_name_to_type);
 
-static const char *get_reason_str(enum kmsg_dump_reason reason)
+static void pstore_timer_kick(void)
 {
-	switch (reason) {
-	case KMSG_DUMP_PANIC:
-		return "Panic";
-	case KMSG_DUMP_OOPS:
-		return "Oops";
-	case KMSG_DUMP_EMERG:
-		return "Emergency";
-	case KMSG_DUMP_RESTART:
-		return "Restart";
-	case KMSG_DUMP_HALT:
-		return "Halt";
-	case KMSG_DUMP_POWEROFF:
-		return "Poweroff";
-	default:
-		return "Unknown";
-	}
+	if (pstore_update_ms < 0)
+		return;
+
+	mod_timer(&pstore_timer, jiffies + msecs_to_jiffies(pstore_update_ms));
 }
 
-/*
- * Should pstore_dump() wait for a concurrent pstore_dump()? If
- * not, the current pstore_dump() will report a failure to dump
- * and return.
- */
-static bool pstore_cannot_wait(enum kmsg_dump_reason reason)
+static bool pstore_cannot_block_path(enum kmsg_dump_reason reason)
 {
-	/* In NMI path, pstore shouldn't block regardless of reason. */
+	/*
+	 * In case of NMI path, pstore shouldn't be blocked
+	 * regardless of reason.
+	 */
 	if (in_nmi())
 		return true;
 
 	switch (reason) {
 	/* In panic case, other cpus are stopped by smp_send_stop(). */
 	case KMSG_DUMP_PANIC:
-	/* Emergency restart shouldn't be blocked. */
+	/*
+	 * Emergency restart shouldn't be blocked by spinning on
+	 * pstore_info::buf_lock.
+	 */
 	case KMSG_DUMP_EMERG:
 		return true;
 	default:
@@ -224,7 +219,7 @@ static int zbufsize_842(size_t size)
 #if IS_ENABLED(CONFIG_PSTORE_ZSTD_COMPRESS)
 static int zbufsize_zstd(size_t size)
 {
-	return ZSTD_compressBound(size);
+	return zstd_compress_bound(size);
 }
 #endif
 
@@ -275,6 +270,9 @@ static int pstore_compress(const void *in, void *out,
 {
 	int ret;
 
+	if (!IS_ENABLED(CONFIG_PSTORE_COMPRESS))
+		return -EINVAL;
+
 	ret = crypto_comp_compress(tfm, in, inlen, out, &outlen);
 	if (ret) {
 		pr_err("crypto_comp_compress failed, ret = %d!\n", ret);
@@ -388,26 +386,27 @@ void pstore_record_init(struct pstore_record *record,
 static void pstore_dump(struct kmsg_dumper *dumper,
 			enum kmsg_dump_reason reason)
 {
+	struct kmsg_dump_iter iter;
 	unsigned long	total = 0;
 	const char	*why;
 	unsigned int	part = 1;
+	unsigned long	flags = 0;
 	int		ret;
 
-	why = get_reason_str(reason);
+	why = kmsg_dump_reason_str(reason);
 
-	if (down_trylock(&psinfo->buf_lock)) {
-		/* Failed to acquire lock: give up if we cannot wait. */
-		if (pstore_cannot_wait(reason)) {
-			pr_err("dump skipped in %s path: may corrupt error record\n",
-				in_nmi() ? "NMI" : why);
-			return;
-		}
-		if (down_interruptible(&psinfo->buf_lock)) {
-			pr_err("could not grab semaphore?!\n");
+	if (pstore_cannot_block_path(reason)) {
+		if (!spin_trylock_irqsave(&psinfo->buf_lock, flags)) {
+			pr_err("dump skipped in %s path because of concurrent dump\n",
+					in_nmi() ? "NMI" : why);
 			return;
 		}
+	} else {
+		spin_lock_irqsave(&psinfo->buf_lock, flags);
 	}
 
+	kmsg_dump_rewind(&iter);
+
 	oopscount++;
 	while (total < kmsg_bytes) {
 		char *dst;
@@ -438,7 +437,7 @@ static void pstore_dump(struct kmsg_dumper *dumper,
 		dst_size -= header_size;
 
 		/* Write dump contents. */
-		if (!kmsg_dump_get_buffer(dumper, true, dst + header_size,
+		if (!kmsg_dump_get_buffer(&iter, true, dst + header_size,
 					  dst_size, &dump_size))
 			break;
 
@@ -459,14 +458,15 @@ static void pstore_dump(struct kmsg_dumper *dumper,
 		}
 
 		ret = psinfo->write(&record);
-		if (ret == 0 && reason == KMSG_DUMP_OOPS && pstore_is_mounted())
+		if (ret == 0 && reason == KMSG_DUMP_OOPS) {
 			pstore_new_entry = 1;
+			pstore_timer_kick();
+		}
 
 		total += record.size;
 		part++;
 	}
-
-	up(&psinfo->buf_lock);
+	spin_unlock_irqrestore(&psinfo->buf_lock, flags);
 }
 
 static struct kmsg_dumper pstore_dumper = {
@@ -503,14 +503,20 @@ static void pstore_console_write(struct console *con, const char *s, unsigned c)
 }
 
 static struct console pstore_console = {
-	.name	= "pstore",
 	.write	= pstore_console_write,
-	.flags	= CON_PRINTBUFFER | CON_ENABLED | CON_ANYTIME,
 	.index	= -1,
 };
 
 static void pstore_register_console(void)
 {
+	/* Show which backend is going to get console writes. */
+	strscpy(pstore_console.name, psinfo->name,
+		sizeof(pstore_console.name));
+	/*
+	 * Always initialize flags here since prior unregister_console()
+	 * calls may have changed settings (specifically CON_ENABLED).
+	 */
+	pstore_console.flags = CON_PRINTBUFFER | CON_ENABLED | CON_ANYTIME;
 	register_console(&pstore_console);
 }
 
@@ -555,8 +561,6 @@ out:
  */
 int pstore_register(struct pstore_info *psi)
 {
-	struct module *owner = psi->owner;
-
 	if (backend && strcmp(backend, psi->name)) {
 		pr_warn("ignoring unexpected backend '%s'\n", psi->name);
 		return -EPERM;
@@ -576,11 +580,11 @@ int pstore_register(struct pstore_info *psi)
 		return -EINVAL;
 	}
 
-	spin_lock(&pstore_lock);
+	mutex_lock(&psinfo_lock);
 	if (psinfo) {
 		pr_warn("backend '%s' already loaded: ignoring '%s'\n",
 			psinfo->name, psi->name);
-		spin_unlock(&pstore_lock);
+		mutex_unlock(&psinfo_lock);
 		return -EBUSY;
 	}
 
@@ -588,22 +592,17 @@ int pstore_register(struct pstore_info *psi)
 		psi->write_user = pstore_write_user_compat;
 	psinfo = psi;
 	mutex_init(&psinfo->read_mutex);
-	sema_init(&psinfo->buf_lock, 1);
-	spin_unlock(&pstore_lock);
-
-	if (owner && !try_module_get(owner)) {
-		psinfo = NULL;
-		return -EINVAL;
-	}
+	spin_lock_init(&psinfo->buf_lock);
 
 	if (psi->flags & PSTORE_FLAGS_DMESG)
 		allocate_buf_for_compression();
 
-	if (pstore_is_mounted())
-		pstore_get_records(0);
+	pstore_get_records(0);
 
-	if (psi->flags & PSTORE_FLAGS_DMESG)
+	if (psi->flags & PSTORE_FLAGS_DMESG) {
+		pstore_dumper.max_reason = psinfo->max_reason;
 		pstore_register_kmsg();
+	}
 	if (psi->flags & PSTORE_FLAGS_CONSOLE)
 		pstore_register_console();
 	if (psi->flags & PSTORE_FLAGS_FTRACE)
@@ -612,33 +611,36 @@ int pstore_register(struct pstore_info *psi)
 		pstore_register_pmsg();
 
 	/* Start watching for new records, if desired. */
-	if (pstore_update_ms >= 0) {
-		pstore_timer.expires = jiffies +
-			msecs_to_jiffies(pstore_update_ms);
-		add_timer(&pstore_timer);
-	}
+	pstore_timer_kick();
 
 	/*
 	 * Update the module parameter backend, so it is visible
 	 * through /sys/module/pstore/parameters/backend
 	 */
-	backend = psi->name;
+	backend = kstrdup(psi->name, GFP_KERNEL);
 
 	pr_info("Registered %s as persistent store backend\n", psi->name);
 
-	module_put(owner);
-
+	mutex_unlock(&psinfo_lock);
 	return 0;
 }
 EXPORT_SYMBOL_GPL(pstore_register);
 
 void pstore_unregister(struct pstore_info *psi)
 {
-	/* Stop timer and make sure all work has finished. */
-	pstore_update_ms = -1;
-	del_timer_sync(&pstore_timer);
-	flush_work(&pstore_work);
+	/* It's okay to unregister nothing. */
+	if (!psi)
+		return;
+
+	mutex_lock(&psinfo_lock);
+
+	/* Only one backend can be registered at a time. */
+	if (WARN_ON(psi != psinfo)) {
+		mutex_unlock(&psinfo_lock);
+		return;
+	}
 
+	/* Unregister all callbacks. */
 	if (psi->flags & PSTORE_FLAGS_PMSG)
 		pstore_unregister_pmsg();
 	if (psi->flags & PSTORE_FLAGS_FTRACE)
@@ -648,10 +650,19 @@ void pstore_unregister(struct pstore_info *psi)
 	if (psi->flags & PSTORE_FLAGS_DMESG)
 		pstore_unregister_kmsg();
 
+	/* Stop timer and make sure all work has finished. */
+	del_timer_sync(&pstore_timer);
+	flush_work(&pstore_work);
+
+	/* Remove all backend records from filesystem tree. */
+	pstore_put_backend_records(psi);
+
 	free_buf_for_compression();
 
 	psinfo = NULL;
+	kfree(backend);
 	backend = NULL;
+	mutex_unlock(&psinfo_lock);
 }
 EXPORT_SYMBOL_GPL(pstore_unregister);
 
@@ -661,7 +672,7 @@ static void decompress_record(struct pstore_record *record)
 	int unzipped_len;
 	char *unzipped, *workspace;
 
-	if (!record->compressed)
+	if (!IS_ENABLED(CONFIG_PSTORE_COMPRESS) || !record->compressed)
 		return;
 
 	/* Only PSTORE_TYPE_DMESG support compression. */
@@ -758,6 +769,7 @@ void pstore_get_backend_records(struct pstore_info *psi,
 		if (rc) {
 			/* pstore_mkfile() did not take record, so free it. */
 			kfree(record->buf);
+			kfree(record->priv);
 			kfree(record);
 			if (rc != -EEXIST || !quiet)
 				failed++;
@@ -788,9 +800,7 @@ static void pstore_timefunc(struct timer_list *unused)
 		schedule_work(&pstore_work);
 	}
 
-	if (pstore_update_ms >= 0)
-		mod_timer(&pstore_timer,
-			  jiffies + msecs_to_jiffies(pstore_update_ms));
+	pstore_timer_kick();
 }
 
 static void __init pstore_choose_compression(void)
@@ -823,9 +833,9 @@ static int __init pstore_init(void)
 
 	ret = pstore_init_fs();
 	if (ret)
-		return ret;
+		free_buf_for_compression();
 
-	return 0;
+	return ret;
 }
 late_initcall(pstore_init);
 
@@ -835,11 +845,5 @@ static void __exit pstore_exit(void)
 }
 module_exit(pstore_exit)
 
-module_param(compress, charp, 0444);
-MODULE_PARM_DESC(compress, "Pstore compression to use");
-
-module_param(backend, charp, 0444);
-MODULE_PARM_DESC(backend, "Pstore backend to use");
-
 MODULE_AUTHOR("Tony Luck <tony.luck@intel.com>");
 MODULE_LICENSE("GPL");