Messages in this thread Patch in this message | | | From | Ming Lei <> | Subject | [RFC PATCH 08/13] driver core: firmware loader: fix device lifetime | Date | Wed, 25 Jul 2012 01:00:08 +0800 |
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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 satisfied easily.
Also this patch holds the reference cound of @device before schedule_work() in request_firmware_nowait() to avoid that the @device dies after request_firmware_nowait returns and before the work is scheduled.
Also request_firmware_nowait should be called in atomic context now, so fix the obsolete comments.
Signed-off-by: Ming Lei <ming.lei@canonical.com> --- drivers/base/firmware_class.c | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-)
diff --git a/drivers/base/firmware_class.c b/drivers/base/firmware_class.c index 674cb11..540b2e1 100644 --- a/drivers/base/firmware_class.c +++ b/drivers/base/firmware_class.c @@ -717,6 +717,8 @@ 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, @@ -798,6 +800,7 @@ 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); @@ -816,9 +819,10 @@ 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. + * it is not possible to sleep for long time. **/ int request_firmware_nowait( @@ -844,6 +848,7 @@ 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; -- 1.7.9.5
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