[PATCH 1/1] EDAC: always return an initialized value in knl_show_interleave_mode

[Nicolas Iooss]

When building drivers/edac/sb_edac.c with compiler warning flags which
aim to detect the use of uninitialized values at compile time, the
compiler reports that knl_show_interleave_mode() may return an
uninitialized value. This function indeed uses a switch statement to set
a local variable ("s"), which is not set to anything in the default
statement. Anyway this would be never reached as
knl_interleave_mode(reg) always returns a value between 0 and 3, but the
compiler has no way of knowing this.

Silent the compiler warning by initializing variable "s" too in the
default case. While at it, make knl_show_interleave_mode() and
show_interleave_mode() return const char* values as the returned
pointers refer to read-only memory.

Signed-off-by: Nicolas Iooss <nicolas.iooss_li...@m4x.org>
---
 drivers/edac/sb_edac.c | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/drivers/edac/sb_edac.c b/drivers/edac/sb_edac.c
index 54ae6dc45ab2..15a068744c25 100644
--- a/drivers/edac/sb_edac.c
+++ b/drivers/edac/sb_edac.c
@@ -304,7 +304,7 @@ struct sbridge_info {
        u64             (*rir_limit)(u32 reg);
        u64             (*sad_limit)(u32 reg);
        u32             (*interleave_mode)(u32 reg);
-       char*           (*show_interleave_mode)(u32 reg);
+       const char*     (*show_interleave_mode)(u32 reg);
        u32             (*dram_attr)(u32 reg);
        const u32       *dram_rule;
        const u32       *interleave_list;
@@ -811,7 +811,7 @@ static u32 interleave_mode(u32 reg)
        return GET_BITFIELD(reg, 1, 1);
 }
 
-char *show_interleave_mode(u32 reg)
+static const char *show_interleave_mode(u32 reg)
 {
        return interleave_mode(reg) ? "8:6" : "[8:6]XOR[18:16]";
 }
@@ -831,9 +831,9 @@ static u32 knl_interleave_mode(u32 reg)
        return GET_BITFIELD(reg, 1, 2);
 }
 
-static char *knl_show_interleave_mode(u32 reg)
+static const char *knl_show_interleave_mode(u32 reg)
 {
-       char *s;
+       const char *s;
 
        switch (knl_interleave_mode(reg)) {
        case 0:
@@ -850,6 +850,7 @@ static char *knl_show_interleave_mode(u32 reg)
                break;
        default:
                WARN_ON(1);
+               s = "";
                break;
        }
 
-- 
2.11.0