Commit 122bda81 authored by David Fries's avatar David Fries Committed by Luis Henriques

w1_therm reference count family data

commit f7134eea upstream.

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: default avatarDavid Fries <David@Fries.net>
Reported-By: default avatarThorsten Bschorr <thorsten@bschorr.de>
Tested-by: default avatarThorsten Bschorr <thorsten@bschorr.de>
Acked-by: default avatarEvgeniy Polyakov <zbr@ioremap.net>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: default avatarLuis Henriques <luis.henriques@canonical.com>
parent 9d140887
...@@ -59,16 +59,32 @@ MODULE_ALIAS("w1-family-" __stringify(W1_THERM_DS28EA00)); ...@@ -59,16 +59,32 @@ MODULE_ALIAS("w1-family-" __stringify(W1_THERM_DS28EA00));
static int w1_strong_pullup = 1; static int w1_strong_pullup = 1;
module_param_named(strong_pullup, w1_strong_pullup, int, 0); 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) 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) if (!sl->family_data)
return -ENOMEM; return -ENOMEM;
atomic_set(THERM_REFCNT(sl->family_data), 1);
return 0; return 0;
} }
static void w1_therm_remove_slave(struct w1_slave *sl) 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); kfree(sl->family_data);
sl->family_data = NULL; sl->family_data = NULL;
} }
...@@ -194,13 +210,22 @@ static ssize_t w1_slave_show(struct device *device, ...@@ -194,13 +210,22 @@ static ssize_t w1_slave_show(struct device *device,
struct w1_slave *sl = dev_to_w1_slave(device); struct w1_slave *sl = dev_to_w1_slave(device);
struct w1_master *dev = sl->master; struct w1_master *dev = sl->master;
u8 rom[9], crc, verdict, external_power; u8 rom[9], crc, verdict, external_power;
int i, max_trying = 10; int i, ret, max_trying = 10;
ssize_t c = PAGE_SIZE; ssize_t c = PAGE_SIZE;
u8 *family_data = sl->family_data;
i = mutex_lock_interruptible(&dev->bus_mutex); ret = mutex_lock_interruptible(&dev->bus_mutex);
if (i != 0) if (ret != 0)
return i; 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)); memset(rom, 0, sizeof(rom));
while (max_trying--) { while (max_trying--) {
...@@ -230,17 +255,19 @@ static ssize_t w1_slave_show(struct device *device, ...@@ -230,17 +255,19 @@ static ssize_t w1_slave_show(struct device *device,
mutex_unlock(&dev->bus_mutex); mutex_unlock(&dev->bus_mutex);
sleep_rem = msleep_interruptible(tm); sleep_rem = msleep_interruptible(tm);
if (sleep_rem != 0) if (sleep_rem != 0) {
return -EINTR; ret = -EINTR;
goto post_unlock;
}
i = mutex_lock_interruptible(&dev->bus_mutex); ret = mutex_lock_interruptible(&dev->bus_mutex);
if (i != 0) if (ret != 0)
return i; goto post_unlock;
} else if (!w1_strong_pullup) { } else if (!w1_strong_pullup) {
sleep_rem = msleep_interruptible(tm); sleep_rem = msleep_interruptible(tm);
if (sleep_rem != 0) { if (sleep_rem != 0) {
mutex_unlock(&dev->bus_mutex); ret = -EINTR;
return -EINTR; goto pre_unlock;
} }
} }
...@@ -269,19 +296,24 @@ static ssize_t w1_slave_show(struct device *device, ...@@ -269,19 +296,24 @@ static ssize_t w1_slave_show(struct device *device,
c -= snprintf(buf + PAGE_SIZE - c, c, ": crc=%02x %s\n", c -= snprintf(buf + PAGE_SIZE - c, c, ": crc=%02x %s\n",
crc, (verdict) ? "YES" : "NO"); crc, (verdict) ? "YES" : "NO");
if (verdict) if (verdict)
memcpy(sl->family_data, rom, sizeof(rom)); memcpy(family_data, rom, sizeof(rom));
else else
dev_warn(device, "Read failed CRC check\n"); dev_warn(device, "Read failed CRC check\n");
for (i = 0; i < 9; ++i) for (i = 0; i < 9; ++i)
c -= snprintf(buf + PAGE_SIZE - c, c, "%02x ", 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", c -= snprintf(buf + PAGE_SIZE - c, c, "t=%d\n",
w1_convert_temp(rom, sl->family->fid)); w1_convert_temp(rom, sl->family->fid));
ret = PAGE_SIZE - c;
pre_unlock:
mutex_unlock(&dev->bus_mutex); 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) static int __init w1_therm_init(void)
......
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