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

6 files changed, 192 insertions, 60 deletions

diff --git a/Documentation/ABI/testing/pstore b/Documentation/ABI/testing/pstore
index ff1df4e3b059..5fca9f5e10a3 100644
--- a/Documentation/ABI/testing/pstore
+++ b/Documentation/ABI/testing/pstore
@@ -1,4 +1,4 @@
-Where:          /dev/pstore/...
+Where:          /sys/fs/pstore/... (or /dev/pstore/...)
 Date:           March 2011
 Kernel Version: 2.6.39
 Contact:        tony.luck@intel.com
@@ -11,9 +11,9 @@ Description:	Generic interface to platform dependent persistent storage.
                 of the console log is captured, but other interesting
                 data can also be saved.
 
-                # mount -t pstore -o kmsg_bytes=8000 - /dev/pstore
+                # mount -t pstore -o kmsg_bytes=8000 - /sys/fs/pstore
 
-                $ ls -l /dev/pstore
+                $ ls -l /sys/fs/pstore/
                 total 0
                 -r--r--r-- 1 root root 7896 Nov 30 15:38 dmesg-erst-1
 
@@ -27,9 +27,9 @@ Description:	Generic interface to platform dependent persistent storage.
                 the file will signal to the underlying persistent storage
                 device that it can reclaim the space for later re-use.
 
-                $ rm /dev/pstore/dmesg-erst-1
+                $ rm /sys/fs/pstore/dmesg-erst-1
 
-                The expectation is that all files in /dev/pstore
+                The expectation is that all files in /sys/fs/pstore/
                 will be saved elsewhere and erased from persistent store
                 soon after boot to free up space ready for the next
                 catastrophe.
diff --git a/drivers/firmware/efivars.c b/drivers/firmware/efivars.c
index f5596db0cf58..fed08b661711 100644
--- a/drivers/firmware/efivars.c
+++ b/drivers/firmware/efivars.c
@@ -158,6 +158,13 @@ efivar_create_sysfs_entry(struct efivars *efivars,
                           efi_char16_t *variable_name,
                           efi_guid_t *vendor_guid);
 
+/*
+ * Prototype for workqueue functions updating sysfs entry
+ */
+
+static void efivar_update_sysfs_entries(struct work_struct *);
+static DECLARE_WORK(efivar_work, efivar_update_sysfs_entries);
+
 /* Return the number of unicode characters in data */
 static unsigned long
 utf16_strnlen(efi_char16_t *s, size_t maxlength)
@@ -405,10 +412,11 @@ static efi_status_t
 get_var_data(struct efivars *efivars, struct efi_variable *var)
 {
         efi_status_t status;
+        unsigned long flags;
 
-        spin_lock(&efivars->lock);
+        spin_lock_irqsave(&efivars->lock, flags);
         status = get_var_data_locked(efivars, var);
-        spin_unlock(&efivars->lock);
+        spin_unlock_irqrestore(&efivars->lock, flags);
 
         if (status != EFI_SUCCESS) {
                 printk(KERN_WARNING "efivars: get_variable() failed 0x%lx!\n",
@@ -537,14 +545,14 @@ efivar_store_raw(struct efivar_entry *entry, const char *buf, size_t count)
                 return -EINVAL;
         }
 
-        spin_lock(&efivars->lock);
+        spin_lock_irq(&efivars->lock);
         status = efivars->ops->set_variable(new_var->VariableName,
                                             &new_var->VendorGuid,
                                             new_var->Attributes,
                                             new_var->DataSize,
                                             new_var->Data);
 
-        spin_unlock(&efivars->lock);
+        spin_unlock_irq(&efivars->lock);
 
         if (status != EFI_SUCCESS) {
                 printk(KERN_WARNING "efivars: set_variable() failed: status=%lx\n",
@@ -713,7 +721,7 @@ static ssize_t efivarfs_file_write(struct file *file,
          * amounts of memory. Pick a default size of 64K if
          * QueryVariableInfo() isn't supported by the firmware.
          */
-        spin_lock(&efivars->lock);
+        spin_lock_irq(&efivars->lock);
 
         if (!efivars->ops->query_variable_info)
                 status = EFI_UNSUPPORTED;
@@ -723,7 +731,7 @@ static ssize_t efivarfs_file_write(struct file *file,
                                                    &remaining_size, &max_size);
         }
 
-        spin_unlock(&efivars->lock);
+        spin_unlock_irq(&efivars->lock);
 
         if (status != EFI_SUCCESS) {
                 if (status != EFI_UNSUPPORTED)
@@ -754,7 +762,7 @@ static ssize_t efivarfs_file_write(struct file *file,
          * set_variable call, and removal of the variable from the efivars
          * list (in the case of an authenticated delete).
          */
-        spin_lock(&efivars->lock);
+        spin_lock_irq(&efivars->lock);
 
         status = efivars->ops->set_variable(var->var.VariableName,
                                             &var->var.VendorGuid,
@@ -762,7 +770,7 @@ static ssize_t efivarfs_file_write(struct file *file,
                                             data);
 
         if (status != EFI_SUCCESS) {
-                spin_unlock(&efivars->lock);
+                spin_unlock_irq(&efivars->lock);
                 kfree(data);
 
                 return efi_status_to_err(status);
@@ -783,21 +791,21 @@ static ssize_t efivarfs_file_write(struct file *file,
                                             NULL);
 
         if (status == EFI_BUFFER_TOO_SMALL) {
-                spin_unlock(&efivars->lock);
+                spin_unlock_irq(&efivars->lock);
                 mutex_lock(&inode->i_mutex);
                 i_size_write(inode, newdatasize + sizeof(attributes));
                 mutex_unlock(&inode->i_mutex);
 
         } else if (status == EFI_NOT_FOUND) {
                 list_del(&var->list);
-                spin_unlock(&efivars->lock);
+                spin_unlock_irq(&efivars->lock);
                 efivar_unregister(var);
                 drop_nlink(inode);
                 d_delete(file->f_dentry);
                 dput(file->f_dentry);
 
         } else {
-                spin_unlock(&efivars->lock);
+                spin_unlock_irq(&efivars->lock);
                 pr_warn("efivarfs: inconsistent EFI variable implementation? "
                                 "status = %lx\n", status);
         }
@@ -819,11 +827,11 @@ static ssize_t efivarfs_file_read(struct file *file, char __user *userbuf,
         void *data;
         ssize_t size = 0;
 
-        spin_lock(&efivars->lock);
+        spin_lock_irq(&efivars->lock);
         status = efivars->ops->get_variable(var->var.VariableName,
                                             &var->var.VendorGuid,
                                             &attributes, &datasize, NULL);
-        spin_unlock(&efivars->lock);
+        spin_unlock_irq(&efivars->lock);
 
         if (status != EFI_BUFFER_TOO_SMALL)
                 return efi_status_to_err(status);
@@ -833,12 +841,12 @@ static ssize_t efivarfs_file_read(struct file *file, char __user *userbuf,
         if (!data)
                 return -ENOMEM;
 
-        spin_lock(&efivars->lock);
+        spin_lock_irq(&efivars->lock);
         status = efivars->ops->get_variable(var->var.VariableName,
                                             &var->var.VendorGuid,
                                             &attributes, &datasize,
                                             (data + sizeof(attributes)));
-        spin_unlock(&efivars->lock);
+        spin_unlock_irq(&efivars->lock);
 
         if (status != EFI_SUCCESS) {
                 size = efi_status_to_err(status);
@@ -966,9 +974,9 @@ static int efivarfs_create(struct inode *dir, struct dentry *dentry,
                 goto out;
 
         kobject_uevent(&var->kobj, KOBJ_ADD);
-        spin_lock(&efivars->lock);
+        spin_lock_irq(&efivars->lock);
         list_add(&var->list, &efivars->list);
-        spin_unlock(&efivars->lock);
+        spin_unlock_irq(&efivars->lock);
         d_instantiate(dentry, inode);
         dget(dentry);
 out:
@@ -985,7 +993,7 @@ static int efivarfs_unlink(struct inode *dir, struct dentry *dentry)
         struct efivars *efivars = var->efivars;
         efi_status_t status;
 
-        spin_lock(&efivars->lock);
+        spin_lock_irq(&efivars->lock);
 
         status = efivars->ops->set_variable(var->var.VariableName,
                                             &var->var.VendorGuid,
@@ -993,14 +1001,14 @@ static int efivarfs_unlink(struct inode *dir, struct dentry *dentry)
 
         if (status == EFI_SUCCESS || status == EFI_NOT_FOUND) {
                 list_del(&var->list);
-                spin_unlock(&efivars->lock);
+                spin_unlock_irq(&efivars->lock);
                 efivar_unregister(var);
                 drop_nlink(dentry->d_inode);
                 dput(dentry);
                 return 0;
         }
 
-        spin_unlock(&efivars->lock);
+        spin_unlock_irq(&efivars->lock);
         return -EINVAL;
 };
 
@@ -1066,13 +1074,13 @@ static int efivarfs_fill_super(struct super_block *sb, void *data, int silent)
                 /* copied by the above to local storage in the dentry. */
                 kfree(name);
 
-                spin_lock(&efivars->lock);
+                spin_lock_irq(&efivars->lock);
                 efivars->ops->get_variable(entry->var.VariableName,
                                            &entry->var.VendorGuid,
                                            &entry->var.Attributes,
                                            &size,
                                            NULL);
-                spin_unlock(&efivars->lock);
+                spin_unlock_irq(&efivars->lock);
 
                 mutex_lock(&inode->i_mutex);
                 inode->i_private = entry;
@@ -1123,7 +1131,7 @@ static int efi_pstore_open(struct pstore_info *psi)
 {
         struct efivars *efivars = psi->data;
 
-        spin_lock(&efivars->lock);
+        spin_lock_irq(&efivars->lock);
         efivars->walk_entry = list_first_entry(&efivars->list,
                                                struct efivar_entry, list);
         return 0;
@@ -1133,7 +1141,7 @@ static int efi_pstore_close(struct pstore_info *psi)
 {
         struct efivars *efivars = psi->data;
 
-        spin_unlock(&efivars->lock);
+        spin_unlock_irq(&efivars->lock);
         return 0;
 }
 
@@ -1209,8 +1217,18 @@ static int efi_pstore_write(enum pstore_type_id type,
         int i, ret = 0;
         u64 storage_space, remaining_space, max_variable_size;
         efi_status_t status = EFI_NOT_FOUND;
-
-        spin_lock(&efivars->lock);
+        unsigned long flags;
+
+        if (pstore_cannot_block_path(reason)) {
+                /*
+                 * If the lock is taken by another cpu in non-blocking path,
+                 * this driver returns without entering firmware to avoid
+                 * hanging up.
+                 */
+                if (!spin_trylock_irqsave(&efivars->lock, flags))
+                        return -EBUSY;
+        } else
+                spin_lock_irqsave(&efivars->lock, flags);
 
         /*
          * Check if there is a space enough to log.
@@ -1222,7 +1240,7 @@ static int efi_pstore_write(enum pstore_type_id type,
                                                    &remaining_space,
                                                    &max_variable_size);
         if (status || remaining_space < size + DUMP_NAME_LEN * 2) {
-                spin_unlock(&efivars->lock);
+                spin_unlock_irqrestore(&efivars->lock, flags);
                 *id = part;
                 return -ENOSPC;
         }
@@ -1236,13 +1254,10 @@ static int efi_pstore_write(enum pstore_type_id type,
         efivars->ops->set_variable(efi_name, &vendor, PSTORE_EFI_ATTRIBUTES,
                                    size, psi->buf);
 
-        spin_unlock(&efivars->lock);
+        spin_unlock_irqrestore(&efivars->lock, flags);
 
-        if (size)
-                ret = efivar_create_sysfs_entry(efivars,
-                                          utf16_strsize(efi_name,
-                                                        DUMP_NAME_LEN * 2),
-                                          efi_name, &vendor);
+        if (reason == KMSG_DUMP_OOPS)
+                schedule_work(&efivar_work);
 
         *id = part;
         return ret;
@@ -1263,7 +1278,7 @@ static int efi_pstore_erase(enum pstore_type_id type, u64 id, int count,
         sprintf(name, "dump-type%u-%u-%d-%lu", type, (unsigned int)id, count,
                 time.tv_sec);
 
-        spin_lock(&efivars->lock);
+        spin_lock_irq(&efivars->lock);
 
         for (i = 0; i < DUMP_NAME_LEN; i++)
                 efi_name[i] = name[i];
@@ -1307,7 +1322,7 @@ static int efi_pstore_erase(enum pstore_type_id type, u64 id, int count,
         if (found)
                 list_del(&found->list);
 
-        spin_unlock(&efivars->lock);
+        spin_unlock_irq(&efivars->lock);
 
         if (found)
                 efivar_unregister(found);
@@ -1377,7 +1392,7 @@ static ssize_t efivar_create(struct file *filp, struct kobject *kobj,
                 return -EINVAL;
         }
 
-        spin_lock(&efivars->lock);
+        spin_lock_irq(&efivars->lock);
 
         /*
          * Does this variable already exist?
@@ -1395,7 +1410,7 @@ static ssize_t efivar_create(struct file *filp, struct kobject *kobj,
                 }
         }
         if (found) {
-                spin_unlock(&efivars->lock);
+                spin_unlock_irq(&efivars->lock);
                 return -EINVAL;
         }
 
@@ -1409,10 +1424,10 @@ static ssize_t efivar_create(struct file *filp, struct kobject *kobj,
         if (status != EFI_SUCCESS) {
                 printk(KERN_WARNING "efivars: set_variable() failed: status=%lx\n",
                         status);
-                spin_unlock(&efivars->lock);
+                spin_unlock_irq(&efivars->lock);
                 return -EIO;
         }
-        spin_unlock(&efivars->lock);
+        spin_unlock_irq(&efivars->lock);
 
         /* Create the entry in sysfs.  Locking is not required here */
         status = efivar_create_sysfs_entry(efivars,
@@ -1440,7 +1455,7 @@ static ssize_t efivar_delete(struct file *filp, struct kobject *kobj,
         if (!capable(CAP_SYS_ADMIN))
                 return -EACCES;
 
-        spin_lock(&efivars->lock);
+        spin_lock_irq(&efivars->lock);
 
         /*
          * Does this variable already exist?
@@ -1458,7 +1473,7 @@ static ssize_t efivar_delete(struct file *filp, struct kobject *kobj,
                 }
         }
         if (!found) {
-                spin_unlock(&efivars->lock);
+                spin_unlock_irq(&efivars->lock);
                 return -EINVAL;
         }
         /* force the Attributes/DataSize to 0 to ensure deletion */
@@ -1474,18 +1489,87 @@ static ssize_t efivar_delete(struct file *filp, struct kobject *kobj,
         if (status != EFI_SUCCESS) {
                 printk(KERN_WARNING "efivars: set_variable() failed: status=%lx\n",
                         status);
-                spin_unlock(&efivars->lock);
+                spin_unlock_irq(&efivars->lock);
                 return -EIO;
         }
         list_del(&search_efivar->list);
         /* We need to release this lock before unregistering. */
-        spin_unlock(&efivars->lock);
+        spin_unlock_irq(&efivars->lock);
         efivar_unregister(search_efivar);
 
         /* It's dead Jim.... */
         return count;
 }
 
+static bool variable_is_present(efi_char16_t *variable_name, efi_guid_t *vendor)
+{
+        struct efivar_entry *entry, *n;
+        struct efivars *efivars = &__efivars;
+        unsigned long strsize1, strsize2;
+        bool found = false;
+
+        strsize1 = utf16_strsize(variable_name, 1024);
+        list_for_each_entry_safe(entry, n, &efivars->list, list) {
+                strsize2 = utf16_strsize(entry->var.VariableName, 1024);
+                if (strsize1 == strsize2 &&
+                        !memcmp(variable_name, &(entry->var.VariableName),
+                                strsize2) &&
+                        !efi_guidcmp(entry->var.VendorGuid,
+                                *vendor)) {
+                        found = true;
+                        break;
+                }
+        }
+        return found;
+}
+
+static void efivar_update_sysfs_entries(struct work_struct *work)
+{
+        struct efivars *efivars = &__efivars;
+        efi_guid_t vendor;
+        efi_char16_t *variable_name;
+        unsigned long variable_name_size = 1024;
+        efi_status_t status = EFI_NOT_FOUND;
+        bool found;
+
+        /* Add new sysfs entries */
+        while (1) {
+                variable_name = kzalloc(variable_name_size, GFP_KERNEL);
+                if (!variable_name) {
+                        pr_err("efivars: Memory allocation failed.\n");
+                        return;
+                }
+
+                spin_lock_irq(&efivars->lock);
+                found = false;
+                while (1) {
+                        variable_name_size = 1024;
+                        status = efivars->ops->get_next_variable(
+                                                        &variable_name_size,
+                                                        variable_name,
+                                                        &vendor);
+                        if (status != EFI_SUCCESS) {
+                                break;
+                        } else {
+                                if (!variable_is_present(variable_name,
+                                    &vendor)) {
+                                        found = true;
+                                        break;
+                                }
+                        }
+                }
+                spin_unlock_irq(&efivars->lock);
+
+                if (!found) {
+                        kfree(variable_name);
+                        break;
+                } else
+                        efivar_create_sysfs_entry(efivars,
+                                                  variable_name_size,
+                                                  variable_name, &vendor);
+        }
+}
+
 /*
  * Let's not leave out systab information that snuck into
  * the efivars driver
@@ -1594,9 +1678,9 @@ efivar_create_sysfs_entry(struct efivars *efivars,
         kfree(short_name);
         short_name = NULL;
 
-        spin_lock(&efivars->lock);
+        spin_lock_irq(&efivars->lock);
         list_add(&new_efivar->list, &efivars->list);
-        spin_unlock(&efivars->lock);
+        spin_unlock_irq(&efivars->lock);
 
         return 0;
 }
@@ -1665,9 +1749,9 @@ void unregister_efivars(struct efivars *efivars)
         struct efivar_entry *entry, *n;
 
         list_for_each_entry_safe(entry, n, &efivars->list, list) {
-                spin_lock(&efivars->lock);
+                spin_lock_irq(&efivars->lock);
                 list_del(&entry->list);
-                spin_unlock(&efivars->lock);
+                spin_unlock_irq(&efivars->lock);
                 efivar_unregister(entry);
         }
         if (efivars->new_var)
@@ -1823,6 +1907,8 @@ err_put:
 static void __exit
 efivars_exit(void)
 {
+        cancel_work_sync(&efivar_work);
+
         if (efi_enabled(EFI_RUNTIME_SERVICES)) {
                 unregister_efivars(&__efivars);
                 kobject_put(efi_kobj);
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);
 }
diff --git a/include/linux/efi.h b/include/linux/efi.h
index 7a9498ab3c2d..9bf2f1fcae27 100644
--- a/include/linux/efi.h
+++ b/include/linux/efi.h
@@ -740,7 +740,8 @@ struct efivars {
          * 1) ->list - adds, removals, reads, writes
          * 2) ops.[gs]et_variable() calls.
          * It must not be held when creating sysfs entries or calling kmalloc.
-         * ops.get_next_variable() is only called from register_efivars(),
+         * ops.get_next_variable() is only called from register_efivars()
+         * or efivar_update_sysfs_entries(),
          * which is protected by the BKL, so that path is safe.
          */
         spinlock_t lock;
diff --git a/include/linux/pstore.h b/include/linux/pstore.h
index 1788909d9a99..75d01760c911 100644
--- a/include/linux/pstore.h
+++ b/include/linux/pstore.h
@@ -68,12 +68,18 @@ struct pstore_info {
 
 #ifdef CONFIG_PSTORE
 extern int pstore_register(struct pstore_info *);
+extern bool pstore_cannot_block_path(enum kmsg_dump_reason reason);
 #else
 static inline int
 pstore_register(struct pstore_info *psi)
 {
         return -ENODEV;
 }
+static inline bool
+pstore_cannot_block_path(enum kmsg_dump_reason reason)
+{
+        return false;
+}
 #endif
 
 #endif /*_LINUX_PSTORE_H*/