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| author | Ming Lei <ming.lei@canonical.com> | 2012-08-04 08:01:23 +0400 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2012-08-17 00:28:50 +0400 |
| commit | 0cfc1e1e7b5347b4b6df1212f365ce6620bdd98f (patch) | |
| tree | 4d976455cea5dc6055c132b0f9833b01afe5c285 /drivers/base | |
| parent | 2887b3959c8b2f6ed1f62ce95c0888aedb1ea84b (diff) | |
| download | linux-0cfc1e1e7b5347b4b6df1212f365ce6620bdd98f.tar.xz | |
firmware loader: fix device lifetime
Callers of request_firmware* must hold the reference count of
@device, otherwise it is easy to trigger oops since the firmware
loader device is the child of @device.
This patch adds comments about the usage. In fact, most of drivers
call request_firmware* in its probe() or open(), so the constraint
should be reasonable and can be satisfied.
Also this patch holds the reference count of @device before
schedule_work() in request_firmware_nowait() to avoid that
the @device is released after request_firmware_nowait returns
and before the worker function is scheduled.
Signed-off-by: Ming Lei <ming.lei@canonical.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/base')
| -rw-r--r-- | drivers/base/firmware_class.c | 6 |
1 files changed, 6 insertions, 0 deletions
diff --git a/drivers/base/firmware_class.c b/drivers/base/firmware_class.c index fc119ce6fdb8..7d3a83bb1318 100644 --- a/drivers/base/firmware_class.c +++ b/drivers/base/firmware_class.c @@ -742,6 +742,8 @@ err_put_dev: * @name will be used as $FIRMWARE in the uevent environment and * should be distinctive enough not to be confused with any other * firmware image for this or any other device. + * + * Caller must hold the reference count of @device. **/ int request_firmware(const struct firmware **firmware_p, const char *name, @@ -823,6 +825,7 @@ static void request_firmware_work_func(struct work_struct *work) out: fw_work->cont(fw, fw_work->context); + put_device(fw_work->device); module_put(fw_work->module); kfree(fw_work); @@ -841,6 +844,8 @@ static void request_firmware_work_func(struct work_struct *work) * @cont: function will be called asynchronously when the firmware * request is over. * + * Caller must hold the reference count of @device. + * * Asynchronous variant of request_firmware() for user contexts where * it is not possible to sleep for long time. It can't be called * in atomic contexts. @@ -869,6 +874,7 @@ request_firmware_nowait( return -EFAULT; } + get_device(fw_work->device); INIT_WORK(&fw_work->work, request_firmware_work_func); schedule_work(&fw_work->work); return 0; |