powerpc/nvram_64: Check nvram_error_log_index in nvram_clear_error_log()

nvram_clear_error_log() calls ppc_md.nvram_write() even when
nvram_error_log_index is -1 (invalid). The nvram_write() function does
not check for a negative offset.

Check nvram_error_log_index as the other nvram log functions do.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: linuxppc-dev@ozlabs.org
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

diff --git a/arch/powerpc/kernel/nvram_64.c b/arch/powerpc/kernel/nvram_64.c
index c67e0102df96fce5f53cb821052dedd763e95d62..89d4af2a13ef0022be92df490f94d93efb2adc8d 100644 (file)
--- a/arch/powerpc/kernel/nvram_64.c
+++ b/arch/powerpc/kernel/nvram_64.c
@@ -681,6 +681,9 @@ int nvram_clear_error_log(void)
        int clear_word = ERR_FLAG_ALREADY_LOGGED;
        int rc;
 
+       if (nvram_error_log_index == -1)
+               return -1;
+
        tmp_index = nvram_error_log_index;
        
        rc = ppc_md.nvram_write((char *)&clear_word, sizeof(int), &tmp_index);