efibc: Report more information in the error messages

Report the name of the EFI variable if the value size is too large,
or if efibc_set_variable() fails to allocate the 'struct efivar_entry'
object.

If efibc_set_variable() fails because the 'size' value is too
large, it also reports this value in the error message.

Reported-by: Robert Elliott <elliott@hpe.com>
Signed-off-by: Jeremy Compostella <jeremy.compostella@intel.com>
Signed-off-by: Matt Fleming <matt@codeblueprint.co.uk>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-efi@vger.kernel.org
Link: http://lkml.kernel.org/r/1466839230-12781-2-git-send-email-matt@codeblueprint.co.uk
[ Minor readability edits. ]
Signed-off-by: Ingo Molnar <mingo@kernel.org>

drivers/firmware/efi/efibc.c

@@ -37,13 +37,13 @@ static int efibc_set_variable(const char *name, const char *value)
 	size_t size = (strlen(value) + 1) * sizeof(efi_char16_t);
 
 	if (size > sizeof(entry->var.Data)) {
-		pr_err("value is too large");
+		pr_err("value is too large (%zu bytes) for '%s' EFI variable\n", size, name);
 		return -EINVAL;
 	}
 
 	entry = kmalloc(sizeof(*entry), GFP_KERNEL);
 	if (!entry) {
-		pr_err("failed to allocate efivar entry");
+		pr_err("failed to allocate efivar entry for '%s' EFI variable\n", name);
 		return -ENOMEM;
 	}