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w1_therm reference count family data

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A temperature conversion can take 750 ms and when possible the
w1_therm slave driver drops the bus_mutex to allow other bus
operations, but that includes operations such as a periodic slave
search, which can remove this slave when it is no longer detected.
If that happens the sl->family_data will be freed and set to NULL
causing w1_slave_show to crash when it wakes up.

Signed-off-by: David Fries <David@Fries.net>
Reported-By: Thorsten Bschorr <thorsten@bschorr.de>
Tested-by: Thorsten Bschorr <thorsten@bschorr.de>
Acked-by: Evgeniy Polyakov <zbr@ioremap.net>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
David Fries 2015-05-08 19:51:50 -05:00 committed by Greg Kroah-Hartman
parent c309835692
commit f7134eea05
1 changed files with 47 additions and 15 deletions
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62
drivers/w1/slaves/w1_therm.c
View File

@ -59,16 +59,32 @@ MODULE_ALIAS("w1-family-" __stringify(W1_THERM_DS28EA00));
static int w1_strong_pullup = 1;
module_param_named(strong_pullup, w1_strong_pullup, int, 0);
struct w1_therm_family_data {
uint8_t rom[9];
atomic_t refcnt;
};
/* return the address of the refcnt in the family data */
#define THERM_REFCNT(family_data) \
(&((struct w1_therm_family_data*)family_data)->refcnt)
static int w1_therm_add_slave(struct w1_slave *sl)
{
sl->family_data = kzalloc(9, GFP_KERNEL);
sl->family_data = kzalloc(sizeof(struct w1_therm_family_data),
GFP_KERNEL);
if (!sl->family_data)
return -ENOMEM;
atomic_set(THERM_REFCNT(sl->family_data), 1);
return 0;
}
static void w1_therm_remove_slave(struct w1_slave *sl)
{
int refcnt = atomic_sub_return(1, THERM_REFCNT(sl->family_data));
while(refcnt) {
msleep(1000);
refcnt = atomic_read(THERM_REFCNT(sl->family_data));
}
kfree(sl->family_data);
sl->family_data = NULL;
}
@ -194,13 +210,22 @@ static ssize_t w1_slave_show(struct device *device,
struct w1_slave *sl = dev_to_w1_slave(device);
struct w1_master *dev = sl->master;
u8 rom[9], crc, verdict, external_power;
int i, max_trying = 10;
int i, ret, max_trying = 10;
ssize_t c = PAGE_SIZE;
u8 *family_data = sl->family_data;
i = mutex_lock_interruptible(&dev->bus_mutex);
if (i != 0)
return i;
ret = mutex_lock_interruptible(&dev->bus_mutex);
if (ret != 0)
goto post_unlock;
if(!sl->family_data)
{
ret = -ENODEV;
goto pre_unlock;
}
/* prevent the slave from going away in sleep */
atomic_inc(THERM_REFCNT(family_data));
memset(rom, 0, sizeof(rom));
while (max_trying--) {
@ -230,17 +255,19 @@ static ssize_t w1_slave_show(struct device *device,
mutex_unlock(&dev->bus_mutex);
sleep_rem = msleep_interruptible(tm);
if (sleep_rem != 0)
return -EINTR;
if (sleep_rem != 0) {
ret = -EINTR;
goto post_unlock;
}
i = mutex_lock_interruptible(&dev->bus_mutex);
if (i != 0)
return i;
ret = mutex_lock_interruptible(&dev->bus_mutex);
if (ret != 0)
goto post_unlock;
} else if (!w1_strong_pullup) {
sleep_rem = msleep_interruptible(tm);
if (sleep_rem != 0) {
mutex_unlock(&dev->bus_mutex);
return -EINTR;
ret = -EINTR;
goto pre_unlock;
}
}
@ -269,19 +296,24 @@ static ssize_t w1_slave_show(struct device *device,
c -= snprintf(buf + PAGE_SIZE - c, c, ": crc=%02x %s\n",
crc, (verdict) ? "YES" : "NO");
if (verdict)
memcpy(sl->family_data, rom, sizeof(rom));
memcpy(family_data, rom, sizeof(rom));
else
dev_warn(device, "Read failed CRC check\n");
for (i = 0; i < 9; ++i)
c -= snprintf(buf + PAGE_SIZE - c, c, "%02x ",
((u8 *)sl->family_data)[i]);
((u8 *)family_data)[i]);
c -= snprintf(buf + PAGE_SIZE - c, c, "t=%d\n",
w1_convert_temp(rom, sl->family->fid));
ret = PAGE_SIZE - c;
pre_unlock:
mutex_unlock(&dev->bus_mutex);
return PAGE_SIZE - c;
post_unlock:
atomic_dec(THERM_REFCNT(family_data));
return ret;
}
static int __init w1_therm_init(void)