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 73e6ff71a7ea924fb7121d576a2d41e3be3fc6b5 upstream.
Super-IO accesses may fail on a system with no or unmapped LPC bus.
Unable to handle kernel paging request at virtual address ffffffbffee0002e pgd = ffffffc1d68d4000 [ffffffbffee0002e] *pgd=0000000000000000, *pud=0000000000000000 Internal error: Oops: 94000046 [#1] PREEMPT SMP Modules linked in: f71805f(+) hwmon CPU: 3 PID: 1659 Comm: insmod Not tainted 4.5.0+ #88 Hardware name: linux,dummy-virt (DT) task: ffffffc1f6665400 ti: ffffffc1d6418000 task.ti: ffffffc1d6418000 PC is at f71805f_find+0x6c/0x358 [f71805f]
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: e53004e20a58e ("hwmon: New f71805f 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/f71805f.c | 15 ++++++++++++--- 1 file changed, 12 insertions(+), 3 deletions(-)
--- a/drivers/hwmon/f71805f.c +++ b/drivers/hwmon/f71805f.c @@ -96,17 +96,23 @@ superio_select(int base, int ld) outb(ld, base + 1); }
-static inline void +static inline int superio_enter(int base) { + if (!request_muxed_region(base, 2, DRVNAME)) + return -EBUSY; + outb(0x87, base); outb(0x87, base); + + return 0; }
static inline void superio_exit(int base) { outb(0xaa, base); + release_region(base, 2); }
/* @@ -1562,7 +1568,7 @@ exit: static int __init f71805f_find(int sioaddr, unsigned short *address, struct f71805f_sio_data *sio_data) { - int err = -ENODEV; + int err; u16 devid;
static const char * const names[] = { @@ -1570,8 +1576,11 @@ static int __init f71805f_find(int sioad "F71872F/FG or F71806F/FG", };
- superio_enter(sioaddr); + err = superio_enter(sioaddr); + if (err) + return err;
+ err = -ENODEV; devid = superio_inw(sioaddr, SIO_REG_MANID); if (devid != SIO_FINTEK_ID) goto exit;