diff options
author | David Fries <David@Fries.net> | 2015-05-09 02:51:50 +0200 |
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committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2015-05-24 21:08:59 +0200 |
commit | f7134eea05b2fb4a2c0935f8a540539fff01f3eb (patch) | |
tree | 756f42e02e8ca03891f7f2c01bb28405a27528b4 /drivers/w1/slaves/w1_therm.c | |
parent | w1: introduce an ability to specify microseconds bus scanning intervals (diff) | |
download | linux-f7134eea05b2fb4a2c0935f8a540539fff01f3eb.tar.xz linux-f7134eea05b2fb4a2c0935f8a540539fff01f3eb.zip |
w1_therm reference count family data
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>
Diffstat (limited to 'drivers/w1/slaves/w1_therm.c')
-rw-r--r-- | drivers/w1/slaves/w1_therm.c | 62 |
1 files changed, 47 insertions, 15 deletions
diff --git a/drivers/w1/slaves/w1_therm.c b/drivers/w1/slaves/w1_therm.c index 1f11a20a8ab9..55eb86c9e214 100644 --- a/drivers/w1/slaves/w1_therm.c +++ b/drivers/w1/slaves/w1_therm.c @@ -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; + + ret = mutex_lock_interruptible(&dev->bus_mutex); + if (ret != 0) + goto post_unlock; - i = mutex_lock_interruptible(&dev->bus_mutex); - if (i != 0) - return i; + 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) |