3.16.74-rc1 review patch. If anyone has any objections, please let me know.
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From: Guenter Roeck linux@roeck-us.net
commit 8c0826756744c0ac1df600a5e4cca1a341b13101 upstream.
Super-IO accesses may fail on a system with no or unmapped LPC bus.
Also, other drivers may attempt to access the LPC bus at the same time, resulting in undefined behavior.
Use request_muxed_region() to ensure that IO access on the requested address space is supported, and to ensure that access by multiple drivers is synchronized.
Fixes: 8d5d45fb1468 ("I2C: Move hwmon drivers (2/3)") Reported-by: Kefeng Wang wangkefeng.wang@huawei.com Reported-by: John Garry john.garry@huawei.com Cc: John Garry john.garry@huawei.com Acked-by: John Garry john.garry@huawei.com Signed-off-by: Guenter Roeck linux@roeck-us.net Signed-off-by: Ben Hutchings ben@decadent.org.uk --- drivers/hwmon/smsc47b397.c | 13 +++++++++++-- 1 file changed, 11 insertions(+), 2 deletions(-)
--- a/drivers/hwmon/smsc47b397.c +++ b/drivers/hwmon/smsc47b397.c @@ -72,14 +72,19 @@ static inline void superio_select(int ld superio_outb(0x07, ld); }
-static inline void superio_enter(void) +static inline int superio_enter(void) { + if (!request_muxed_region(REG, 2, DRVNAME)) + return -EBUSY; + outb(0x55, REG); + return 0; }
static inline void superio_exit(void) { outb(0xAA, REG); + release_region(REG, 2); }
#define SUPERIO_REG_DEVID 0x20 @@ -338,8 +343,12 @@ static int __init smsc47b397_find(void) u8 id, rev; char *name; unsigned short addr; + int err; + + err = superio_enter(); + if (err) + return err;
- superio_enter(); id = force_id ? force_id : superio_inb(SUPERIO_REG_DEVID);
switch (id) {