Merge tag 'please-pull-pstore' of git://git.kernel.org/pub/scm/linux/kernel/git/aegl/linux

Pull pstore patches from Tony Luck:
 "A few fixes to reduce places where pstore might hang a system in the
  crash path.  Plus a new mountpoint (/sys/fs/pstore ...  makes more
  sense then /dev/pstore)."

Fix up trivial conflict in drivers/firmware/efivars.c

* tag 'please-pull-pstore' of git://git.kernel.org/pub/scm/linux/kernel/git/aegl/linux:
  pstore: Create a convenient mount point for pstore
  efi_pstore: Introducing workqueue updating sysfs
  efivars: Disable external interrupt while holding efivars->lock
  efi_pstore: Avoid deadlock in non-blocking paths
  pstore: Avoid deadlock in panic and emergency-restart path

2 files changed, 46 insertions, 7 deletions

diff --git a/fs/pstore/inode.c b/fs/pstore/inode.c
index 67de74ca85f4..e4bcb2cf055a 100644
--- a/fs/pstore/inode.c
+++ b/fs/pstore/inode.c
@@ -418,9 +418,25 @@ static struct file_system_type pstore_fs_type = {
         .kill_sb        = pstore_kill_sb,
 };
 
+static struct kobject *pstore_kobj;
+
 static int __init init_pstore_fs(void)
 {
-        return register_filesystem(&pstore_fs_type);
+        int err = 0;
+
+        /* Create a convenient mount point for people to access pstore */
+        pstore_kobj = kobject_create_and_add("pstore", fs_kobj);
+        if (!pstore_kobj) {
+                err = -ENOMEM;
+                goto out;
+        }
+
+        err = register_filesystem(&pstore_fs_type);
+        if (err < 0)
+                kobject_put(pstore_kobj);
+
+out:
+        return err;
 }
 module_init(init_pstore_fs)
 
diff --git a/fs/pstore/platform.c b/fs/pstore/platform.c
index 5ea2e77ff023..86d1038b5a12 100644
--- a/fs/pstore/platform.c
+++ b/fs/pstore/platform.c
@@ -96,6 +96,27 @@ static const char *get_reason_str(enum kmsg_dump_reason reason)
         }
 }
 
+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
@@ -114,10 +135,12 @@ static void pstore_dump(struct kmsg_dumper *dumper,
 
         why = get_reason_str(reason);
 
-        if (in_nmi()) {
-                is_locked = spin_trylock(&psinfo->buf_lock);
-                if (!is_locked)
-                        pr_err("pstore dump routine blocked in NMI, may corrupt error record\n");
+        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++;
@@ -143,9 +166,9 @@ static void pstore_dump(struct kmsg_dumper *dumper,
                 total += hsize + len;
                 part++;
         }
-        if (in_nmi()) {
+        if (pstore_cannot_block_path(reason)) {
                 if (is_locked)
-                        spin_unlock(&psinfo->buf_lock);
+                        spin_unlock_irqrestore(&psinfo->buf_lock, flags);
         } else
                 spin_unlock_irqrestore(&psinfo->buf_lock, flags);
 }