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 755a9b0f8aaa5639ba5671ca50080852babb89ce 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: ba224e2c4f0a7 ("hwmon: New PC87427 hardware monitoring driver") 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/pc87427.c | 14 +++++++++++++- 1 file changed, 13 insertions(+), 1 deletion(-)
--- a/drivers/hwmon/pc87427.c +++ b/drivers/hwmon/pc87427.c @@ -106,6 +106,13 @@ static const char *logdev_str[2] = { DRV #define LD_IN 1 #define LD_TEMP 1
+static inline int superio_enter(int sioaddr) +{ + if (!request_muxed_region(sioaddr, 2, DRVNAME)) + return -EBUSY; + return 0; +} + static inline void superio_outb(int sioaddr, int reg, int val) { outb(reg, sioaddr); @@ -122,6 +129,7 @@ static inline void superio_exit(int sioa { outb(0x02, sioaddr); outb(0x02, sioaddr + 1); + release_region(sioaddr, 2); }
/* @@ -1221,7 +1229,11 @@ static int __init pc87427_find(int sioad { u16 val; u8 cfg, cfg_b; - int i, err = 0; + int i, err; + + err = superio_enter(sioaddr); + if (err) + return err;
/* Identify device */ val = force_id ? force_id : superio_inb(sioaddr, SIOREG_DEVID);