| Message ID | 20180704084550.7565-1-enric.balletbo@collabora.com (mailing list archive) |
|---|---|
| State | Not Applicable, archived |
| Headers | show |
Hi Enric, 2018-07-04 17:45 GMT+09:00 Enric Balletbo i Serra <enric.balletbo@collabora.com>: > When the devfreq driver and the governor driver are built as modules, > the call to devfreq_add_device() or governor_store() fails because the > governor driver is not loaded at the time the devfreq driver loads. The > devfreq driver has a build dependency on the governor but also should > have a runtime dependency. We need to make sure that the governor driver > is loaded before the devfreq driver. > > This patch fixes this bug by adding a try_then_request_governor() > function. First tries to find the governor, and then, if it is not found, > it requests the module and tries again. > > Fixes: 1b5c1be2c88e (PM / devfreq: map devfreq drivers to governor using name) > Signed-off-by: Enric Balletbo i Serra <enric.balletbo@collabora.com> > --- > > Changes in v5: > - Requested by MyungJoo and Chanwoo. > - Fix returning without the lock acquired after request_module. > - Requested by Chanwoo. > - In request governor function check if governor name is NULL or not. > - Remove some unrelated changes (added/removed some blank lines). > > Changes in v4: > - Kept "locked" devfreq_list from the return of find_devfreq_governor() to > the unlock of governor_store(). Requested by MyungJoo Ham. > > Changes in v3: > - Remove unneded change in dev_err message. > - Fix err returned value in case to not find the governor. > > Changes in v2: > - Add a new function to request the module and call that function from > devfreq_add_device and governor_store. > > drivers/devfreq/devfreq.c | 53 ++++++++++++++++++++++++++++++++++++--- > 1 file changed, 49 insertions(+), 4 deletions(-) > > diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c > index 0b5b3abe054e..aa92fbf9f0dd 100644 > --- a/drivers/devfreq/devfreq.c > +++ b/drivers/devfreq/devfreq.c (snip) Looks good to me. Reviewed-by: Chanwoo Choi <cw00.choi@samsung.com> Best Regards, Chanwoo Choi
Hi MyungJoo, On 05/07/18 02:13, Chanwoo Choi wrote: > Hi Enric, > > 2018-07-04 17:45 GMT+09:00 Enric Balletbo i Serra > <enric.balletbo@collabora.com>: >> When the devfreq driver and the governor driver are built as modules, >> the call to devfreq_add_device() or governor_store() fails because the >> governor driver is not loaded at the time the devfreq driver loads. The >> devfreq driver has a build dependency on the governor but also should >> have a runtime dependency. We need to make sure that the governor driver >> is loaded before the devfreq driver. >> >> This patch fixes this bug by adding a try_then_request_governor() >> function. First tries to find the governor, and then, if it is not found, >> it requests the module and tries again. >> >> Fixes: 1b5c1be2c88e (PM / devfreq: map devfreq drivers to governor using name) >> Signed-off-by: Enric Balletbo i Serra <enric.balletbo@collabora.com> >> --- >> >> Changes in v5: >> - Requested by MyungJoo and Chanwoo. >> - Fix returning without the lock acquired after request_module. >> - Requested by Chanwoo. >> - In request governor function check if governor name is NULL or not. >> - Remove some unrelated changes (added/removed some blank lines). >> >> Changes in v4: >> - Kept "locked" devfreq_list from the return of find_devfreq_governor() to >> the unlock of governor_store(). Requested by MyungJoo Ham. >> >> Changes in v3: >> - Remove unneded change in dev_err message. >> - Fix err returned value in case to not find the governor. >> >> Changes in v2: >> - Add a new function to request the module and call that function from >> devfreq_add_device and governor_store. >> >> drivers/devfreq/devfreq.c | 53 ++++++++++++++++++++++++++++++++++++--- >> 1 file changed, 49 insertions(+), 4 deletions(-) >> >> diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c >> index 0b5b3abe054e..aa92fbf9f0dd 100644 >> --- a/drivers/devfreq/devfreq.c >> +++ b/drivers/devfreq/devfreq.c > > (snip) > > Looks good to me. > Reviewed-by: Chanwoo Choi <cw00.choi@samsung.com> > I was expecting see also this patch in the pull request you did but I didn't see. Is because of will be merged as a fix in current cycle? or has been forgotten? Best regards, Enric > Best Regards, > Chanwoo Choi >
diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c index 0b5b3abe054e..aa92fbf9f0dd 100644 --- a/drivers/devfreq/devfreq.c +++ b/drivers/devfreq/devfreq.c @@ -11,6 +11,7 @@ */ #include <linux/kernel.h> +#include <linux/kmod.h> #include <linux/sched.h> #include <linux/errno.h> #include <linux/err.h> @@ -221,6 +222,49 @@ static struct devfreq_governor *find_devfreq_governor(const char *name) return ERR_PTR(-ENODEV); } +/** + * try_then_request_governor() - Try to find the governor and request the + * module if is not found. + * @name: name of the governor + * + * Search the list of devfreq governors and request the module and try again + * if is not found. This can happen when both drivers (the governor driver + * and the driver that call devfreq_add_device) are built as modules. + * devfreq_list_lock should be held by the caller. Returns the matched + * governor's pointer. + */ +static struct devfreq_governor *try_then_request_governor(const char *name) +{ + struct devfreq_governor *governor; + int err = 0; + + if (IS_ERR_OR_NULL(name)) { + pr_err("DEVFREQ: %s: Invalid parameters\n", __func__); + return ERR_PTR(-EINVAL); + } + WARN(!mutex_is_locked(&devfreq_list_lock), + "devfreq_list_lock must be locked."); + + governor = find_devfreq_governor(name); + if (IS_ERR(governor)) { + mutex_unlock(&devfreq_list_lock); + + if (!strncmp(name, DEVFREQ_GOV_SIMPLE_ONDEMAND, + DEVFREQ_NAME_LEN)) + err = request_module("governor_%s", "simpleondemand"); + else + err = request_module("governor_%s", name); + /* Restore previous state before return */ + mutex_lock(&devfreq_list_lock); + if (err) + return NULL; + + governor = find_devfreq_governor(name); + } + + return governor; +} + static int devfreq_notify_transition(struct devfreq *devfreq, struct devfreq_freqs *freqs, unsigned int state) { @@ -645,9 +689,8 @@ struct devfreq *devfreq_add_device(struct device *dev, mutex_unlock(&devfreq->lock); mutex_lock(&devfreq_list_lock); - list_add(&devfreq->node, &devfreq_list); - governor = find_devfreq_governor(devfreq->governor_name); + governor = try_then_request_governor(devfreq->governor_name); if (IS_ERR(governor)) { dev_err(dev, "%s: Unable to find governor for the device\n", __func__); @@ -663,12 +706,14 @@ struct devfreq *devfreq_add_device(struct device *dev, __func__); goto err_init; } + + list_add(&devfreq->node, &devfreq_list); + mutex_unlock(&devfreq_list_lock); return devfreq; err_init: - list_del(&devfreq->node); mutex_unlock(&devfreq_list_lock); device_unregister(&devfreq->dev); @@ -989,7 +1034,7 @@ static ssize_t governor_store(struct device *dev, struct device_attribute *attr, return -EINVAL; mutex_lock(&devfreq_list_lock); - governor = find_devfreq_governor(str_governor); + governor = try_then_request_governor(str_governor); if (IS_ERR(governor)) { ret = PTR_ERR(governor); goto out;
When the devfreq driver and the governor driver are built as modules, the call to devfreq_add_device() or governor_store() fails because the governor driver is not loaded at the time the devfreq driver loads. The devfreq driver has a build dependency on the governor but also should have a runtime dependency. We need to make sure that the governor driver is loaded before the devfreq driver. This patch fixes this bug by adding a try_then_request_governor() function. First tries to find the governor, and then, if it is not found, it requests the module and tries again. Fixes: 1b5c1be2c88e (PM / devfreq: map devfreq drivers to governor using name) Signed-off-by: Enric Balletbo i Serra <enric.balletbo@collabora.com> --- Changes in v5: - Requested by MyungJoo and Chanwoo. - Fix returning without the lock acquired after request_module. - Requested by Chanwoo. - In request governor function check if governor name is NULL or not. - Remove some unrelated changes (added/removed some blank lines). Changes in v4: - Kept "locked" devfreq_list from the return of find_devfreq_governor() to the unlock of governor_store(). Requested by MyungJoo Ham. Changes in v3: - Remove unneded change in dev_err message. - Fix err returned value in case to not find the governor. Changes in v2: - Add a new function to request the module and call that function from devfreq_add_device and governor_store. drivers/devfreq/devfreq.c | 53 ++++++++++++++++++++++++++++++++++++--- 1 file changed, 49 insertions(+), 4 deletions(-)