[PATCH] BUG: pinmux: forbid mux_usecount to be set at UINT_MAX

From: Richard Genoud
Date: Thu Mar 21 2013 - 07:22:13 EST

If pin_free is called on a pin already freed, mux_usecount is set to
UINT_MAX which is really a bad idea.
This will issue a warning, so that we can correct the code responsible
for the double free.

Signed-off-by: Richard Genoud <richard.genoud@xxxxxxxxx>
Ok Stephen, your idea (and code) seems better.
I signed-off it, but it's really yours...
Feel free to transform my Signed-off-by in a Tested-by

drivers/pinctrl/pinmux.c | 5 +++++
1 files changed, 5 insertions(+), 0 deletions(-)

diff --git a/drivers/pinctrl/pinmux.c b/drivers/pinctrl/pinmux.c
index 1a00658..bd83c8b 100644
--- a/drivers/pinctrl/pinmux.c
+++ b/drivers/pinctrl/pinmux.c
@@ -194,6 +194,11 @@ static const char *pin_free(struct pinctrl_dev *pctldev, int pin,

if (!gpio_range) {
+ /*
+ * A pin should not be freed more times than allocated.
+ */
+ if (WARN_ON(!desc->mux_usecount))
+ return NULL;
if (desc->mux_usecount)
return NULL;

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