efivars: pstore: Do not check size when erasing variable

commit 80a19debc2f2d398cfa57fae97bc99826748a602 upstream.

In 3.2, unlike mainline, efi_pstore_erase() calls efi_pstore_write()
with a size of 0, as the underlying EFI interface treats a size of 0
as meaning deletion.

This was not taken into account in my backport of commit d80a361d779a
'efi_pstore: Check remaining space with QueryVariableInfo() before
writing data'.  The size check should be omitted when erasing.

Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Cc: Rui Xiang <rui.xiang@huawei.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/firmware/efivars.c b/drivers/firmware/efivars.c
index c3ac356..787cd2f 100644 (file)
--- a/drivers/firmware/efivars.c
+++ b/drivers/firmware/efivars.c
@@ -778,19 +778,21 @@ static int efi_pstore_write(enum pstore_type_id type,
 
        spin_lock_irqsave(&efivars->lock, flags);
 
-       /*
-        * Check if there is a space enough to log.
-        * size: a size of logging data
-        * DUMP_NAME_LEN * 2: a maximum size of variable name
-        */
-
-       status = check_var_size_locked(efivars, PSTORE_EFI_ATTRIBUTES,
-                                        size + DUMP_NAME_LEN * 2);
-
-       if (status) {
-               spin_unlock_irqrestore(&efivars->lock, flags);
-               *id = part;
-               return -ENOSPC;
+       if (size) {
+               /*
+                * Check if there is a space enough to log.
+                * size: a size of logging data
+                * DUMP_NAME_LEN * 2: a maximum size of variable name
+                */
+
+               status = check_var_size_locked(efivars, PSTORE_EFI_ATTRIBUTES,
+                                              size + DUMP_NAME_LEN * 2);
+
+               if (status) {
+                       spin_unlock_irqrestore(&efivars->lock, flags);
+                       *id = part;
+                       return -ENOSPC;
+               }
        }
 
        for (i = 0; i < DUMP_NAME_LEN; i++)