On 04/04/2019 19:33, Guenter Roeck wrote:
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@xxxxxxxxxx>
Reported-by: John Garry <john.garry@xxxxxxxxxx>
Cc: John Garry <john.garry@xxxxxxxxxx>
Acked-by: John Garry <john.garry@xxxxxxxxxx>
Signed-off-by: Guenter Roeck <linux@xxxxxxxxxxxx>
---
drivers/hwmon/smsc47m1.c | 13 +++++++++++--
1 file changed, 11 insertions(+), 2 deletions(-)
diff --git a/drivers/hwmon/smsc47m1.c b/drivers/hwmon/smsc47m1.c
index c7b6a425e2c0..0736ca6a3aee 100644
--- a/drivers/hwmon/smsc47m1.c
+++ b/drivers/hwmon/smsc47m1.c
@@ -73,16 +73,21 @@ superio_inb(int reg)
/* logical device for fans is 0x0A */
#define superio_select() superio_outb(0x07, 0x0A)
-static inline 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_ACT 0x30
@@ -531,8 +536,12 @@ static int __init smsc47m1_find(struct smsc47m1_sio_data *sio_data)
{
u8 val;
unsigned short addr;
+ int err;
+
+ err = superio_enter();
+ if (err)
+ return err;
- superio_enter();
val = force_id ? force_id : superio_inb(SUPERIO_REG_DEVID);
/*
