1 files changed, 115 insertions, 24 deletions

diff --git a/fs/pstore/platform.c b/fs/pstore/platform.c
index f2c3ff2..45d18d1 100644
--- a/fs/pstore/platform.c
+++ b/fs/pstore/platform.c
@@ -25,18 +25,38 @@
 #include <linux/module.h>
 #include <linux/pstore.h>
 #include <linux/string.h>
+#include <linux/timer.h>
 #include <linux/slab.h>
 #include <linux/uaccess.h>
+#include <linux/hardirq.h>
+#include <linux/workqueue.h>
 
 #include "internal.h"
 
 /*
+ * We defer making "oops" entries appear in pstore - see
+ * whether the system is actually still running well enough
+ * to let someone see the entry
+ */
+#define	PSTORE_INTERVAL	(60 * HZ)
+
+static int pstore_new_entry;
+
+static void pstore_timefunc(unsigned long);
+static DEFINE_TIMER(pstore_timer, pstore_timefunc, 0, 0);
+
+static void pstore_dowork(struct work_struct *);
+static DECLARE_WORK(pstore_work, pstore_dowork);
+
+/*
  * pstore_lock just protects "psinfo" during
  * calls to pstore_register()
  */
 static DEFINE_SPINLOCK(pstore_lock);
 static struct pstore_info *psinfo;
 
+static char *backend;
+
 /* How much of the console log to snapshot */
 static unsigned long kmsg_bytes = 10240;
 
@@ -52,6 +72,27 @@ static char *reason_str[] = {
 	"Oops", "Panic", "Kexec", "Restart", "Halt", "Poweroff", "Emergency"
 };
 
+bool pstore_cannot_block_path(enum kmsg_dump_reason 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 by spin lock. */
+	case KMSG_DUMP_EMERG:
+		return true;
+	default:
+		return false;
+	}
+}
+EXPORT_SYMBOL_GPL(pstore_cannot_block_path);
+
 /*
  * callback from kmsg_dump. (s2,l2) has the most recently
  * written bytes, older bytes are in (s1,l1). Save as much
@@ -67,18 +108,28 @@ static void pstore_dump(struct kmsg_dumper *dumper,
 	unsigned long	size, total = 0;
 	char		*dst, *why;
 	u64		id;
-	int		hsize, part = 1;
+	int		hsize, ret;
+	unsigned int	part = 1;
+	unsigned long	flags = 0;
+	int		is_locked = 0;
 
 	if (reason < ARRAY_SIZE(reason_str))
 		why = reason_str[reason];
 	else
 		why = "Unknown";
 
-	mutex_lock(&psinfo->buf_mutex);
+	if (pstore_cannot_block_path(reason)) {
+		is_locked = spin_trylock_irqsave(&psinfo->buf_lock, flags);
+		if (!is_locked) {
+			pr_err("pstore dump routine blocked in %s path, may corrupt error record\n"
+				       , in_nmi() ? "NMI" : why);
+		}
+	} else
+		spin_lock_irqsave(&psinfo->buf_lock, flags);
 	oopscount++;
 	while (total < kmsg_bytes) {
 		dst = psinfo->buf;
-		hsize = sprintf(dst, "%s#%d Part%d\n", why, oopscount, part++);
+		hsize = sprintf(dst, "%s#%d Part%d\n", why, oopscount, part);
 		size = psinfo->bufsize - hsize;
 		dst += hsize;
 
@@ -94,16 +145,20 @@ static void pstore_dump(struct kmsg_dumper *dumper,
 		memcpy(dst, s1 + s1_start, l1_cpy);
 		memcpy(dst + l1_cpy, s2 + s2_start, l2_cpy);
 
-		id = psinfo->write(PSTORE_TYPE_DMESG, hsize + l1_cpy + l2_cpy);
-		if (reason == KMSG_DUMP_OOPS && pstore_is_mounted())
-			pstore_mkfile(PSTORE_TYPE_DMESG, psinfo->name, id,
-				      psinfo->buf, hsize + l1_cpy + l2_cpy,
-				      CURRENT_TIME, psinfo->erase);
+		ret = psinfo->write(PSTORE_TYPE_DMESG, &id, part,
+				   hsize + l1_cpy + l2_cpy, psinfo);
+		if (ret == 0 && reason == KMSG_DUMP_OOPS && pstore_is_mounted())
+			pstore_new_entry = 1;
 		l1 -= l1_cpy;
 		l2 -= l2_cpy;
 		total += l1_cpy + l2_cpy;
+		part++;
 	}
-	mutex_unlock(&psinfo->buf_mutex);
+	if (pstore_cannot_block_path(reason)) {
+		if (is_locked)
+			spin_unlock_irqrestore(&psinfo->buf_lock, flags);
+	} else
+		spin_unlock_irqrestore(&psinfo->buf_lock, flags);
 }
 
 static struct kmsg_dumper pstore_dumper = {
@@ -128,7 +183,14 @@ int pstore_register(struct pstore_info *psi)
 		spin_unlock(&pstore_lock);
 		return -EBUSY;
 	}
+
+	if (backend && strcmp(backend, psi->name)) {
+		spin_unlock(&pstore_lock);
+		return -EINVAL;
+	}
+
 	psinfo = psi;
+	mutex_init(&psinfo->read_mutex);
 	spin_unlock(&pstore_lock);
 
 	if (owner && !try_module_get(owner)) {
@@ -137,21 +199,27 @@ int pstore_register(struct pstore_info *psi)
 	}
 
 	if (pstore_is_mounted())
-		pstore_get_records();
+		pstore_get_records(0);
 
 	kmsg_dump_register(&pstore_dumper);
 
+	pstore_timer.expires = jiffies + PSTORE_INTERVAL;
+	add_timer(&pstore_timer);
+
 	return 0;
 }
 EXPORT_SYMBOL_GPL(pstore_register);
 
 /*
- * Read all the records from the persistent store. Create and
- * file files in our filesystem.
+ * Read all the records from the persistent store. Create
+ * files in our filesystem.  Don't warn about -EEXIST errors
+ * when we are re-scanning the backing store looking to add new
+ * error records.
  */
-void pstore_get_records(void)
+void pstore_get_records(int quiet)
 {
 	struct pstore_info *psi = psinfo;
+	char			*buf = NULL;
 	ssize_t			size;
 	u64			id;
 	enum pstore_type_id	type;
@@ -161,32 +229,52 @@ void pstore_get_records(void)
 	if (!psi)
 		return;
 
-	mutex_lock(&psinfo->buf_mutex);
+	mutex_lock(&psi->read_mutex);
 	rc = psi->open(psi);
 	if (rc)
 		goto out;
 
-	while ((size = psi->read(&id, &type, &time)) > 0) {
-		if (pstore_mkfile(type, psi->name, id, psi->buf, (size_t)size,
-				  time, psi->erase))
+	while ((size = psi->read(&id, &type, &time, &buf, psi)) > 0) {
+		rc = pstore_mkfile(type, psi->name, id, buf, (size_t)size,
+				  time, psi);
+		kfree(buf);
+		buf = NULL;
+		if (rc && (rc != -EEXIST || !quiet))
 			failed++;
 	}
 	psi->close(psi);
 out:
-	mutex_unlock(&psinfo->buf_mutex);
+	mutex_unlock(&psi->read_mutex);
 
 	if (failed)
 		printk(KERN_WARNING "pstore: failed to load %d record(s) from '%s'\n",
 		       failed, psi->name);
 }
 
+static void pstore_dowork(struct work_struct *work)
+{
+	pstore_get_records(1);
+}
+
+static void pstore_timefunc(unsigned long dummy)
+{
+	if (pstore_new_entry) {
+		pstore_new_entry = 0;
+		schedule_work(&pstore_work);
+	}
+
+	mod_timer(&pstore_timer, jiffies + PSTORE_INTERVAL);
+}
+
 /*
  * Call platform driver to write a record to the
  * persistent store.
  */
 int pstore_write(enum pstore_type_id type, char *buf, size_t size)
 {
-	u64	id;
+	u64		id;
+	int		ret;
+	unsigned long	flags;
 
 	if (!psinfo)
 		return -ENODEV;
@@ -194,14 +282,17 @@ int pstore_write(enum pstore_type_id type, char *buf, size_t size)
 	if (size > psinfo->bufsize)
 		return -EFBIG;
 
-	mutex_lock(&psinfo->buf_mutex);
+	spin_lock_irqsave(&psinfo->buf_lock, flags);
 	memcpy(psinfo->buf, buf, size);
-	id = psinfo->write(type, size);
-	if (pstore_is_mounted())
+	ret = psinfo->write(type, &id, 0, size, psinfo);
+	if (ret == 0 && pstore_is_mounted())
 		pstore_mkfile(PSTORE_TYPE_DMESG, psinfo->name, id, psinfo->buf,
-			      size, CURRENT_TIME, psinfo->erase);
-	mutex_unlock(&psinfo->buf_mutex);
+			      size, CURRENT_TIME, psinfo);
+	spin_unlock_irqrestore(&psinfo->buf_lock, flags);
 
 	return 0;
 }
 EXPORT_SYMBOL_GPL(pstore_write);
+
+module_param(backend, charp, 0444);
+MODULE_PARM_DESC(backend, "Pstore backend to use");