| Message ID | d0200ee9e30de19f69ca1b7e53a8cd7a047fa436.1400595283.git.viresh.kumar@linaro.org |
|---|---|
| State | New |
| Headers | show |
On 05/20/2014 09:17 AM, Viresh Kumar wrote: > From: Chander Kashyap <k.chander@samsung.com> > > We don't have any protection against addition of duplicate OPPs currently and > in case some code tries to add them it will end up corrupting OPP tables. > > There can be many combinations in which we may end up trying duplicate OPPs: > - both freq and volt are same, but earlier OPP may or may not be active. > - only freq is same and volt is different. > > This patch tries to implement below logic for these cases: > > Return 0 if new OPP was duplicate of existing one (i.e. same freq and volt) and > return -EEXIST if new OPP had same freq but different volt as of an existing OPP > OR if both freq/volt were same but earlier OPP was disabled. > > Signed-off-by: Chander Kashyap <k.chander@samsung.com> > Signed-off-by: Inderpal Singh <inderpal.s@samsung.com> > Signed-off-by: Viresh Kumar <viresh.kumar@linrao.org> > --- > V3->V4: > - handle duplicate OPPs more appropriately > - update comment over routine and enhance commit log > > @Chander: I have kept your authorship as is, hope you don't mind me sending it > on your behalf :) > > drivers/base/power/opp.c | 25 +++++++++++++++++++++++-- > 1 file changed, 23 insertions(+), 2 deletions(-) > > diff --git a/drivers/base/power/opp.c b/drivers/base/power/opp.c > index 2553867..cd9af42 100644 > --- a/drivers/base/power/opp.c > +++ b/drivers/base/power/opp.c > @@ -389,6 +389,11 @@ EXPORT_SYMBOL_GPL(dev_pm_opp_find_freq_floor); > * The opp is made available by default and it can be controlled using > * dev_pm_opp_enable/disable functions. > * > + * Duplicate OPPs are discarded. Will return 0 if new OPP was duplicate of > + * existing one (i.e. same freq and volt) and -EEXIST would be returned if new > + * OPP had same freq but different volt as of an existing OPP OR if both were > + * same but earlier OPP was disabled. How about we use the kernel-doc's "Return:" Return: Returns 0 if new OPP was successfully added OR if the new OPP was exact duplicate of existing one (i.e. same frequency and volt). -EEXIST would be returned if new OPP had same freq but different volt as of an existing OPP OR if both were same but earlier OPP was disabled. -ENOMEM is returned if there is no memory available to allocate requisite internal structures. > + * > * Locking: The internal device_opp and opp structures are RCU protected. > * Hence this function internally uses RCU updater strategy with mutex locks > * to keep the integrity of the internal data structures. Callers should ensure > @@ -443,15 +448,31 @@ int dev_pm_opp_add(struct device *dev, unsigned long freq, unsigned long u_volt) > new_opp->u_volt = u_volt; > new_opp->available = true; > > - /* Insert new OPP in order of increasing frequency */ > + /* > + * Insert new OPP in order of increasing frequency > + * and discard if already present > + */ > head = &dev_opp->opp_list; > list_for_each_entry_rcu(opp, &dev_opp->opp_list, node) { > - if (new_opp->rate < opp->rate) > + if (new_opp->rate <= opp->rate) > break; > else > head = &opp->node; > } > > + /* Duplicate OPPs ? */ > + if (new_opp->rate == opp->rate) { > + int ret = (new_opp->u_volt == opp->u_volt) && opp->available ? > + 0 : -EEXIST; > + > + pr_warn("%s: duplicate OPPs detected. Existing: freq: %lu, volt: %lu, enabled: %d. New: freq: %lu, volt: %lu, enabled: %d\n", dev_warn please? we already know the dev pointer. Also can we reduce this down to 80 character limit if possible? > + __func__, opp->rate, opp->u_volt, opp->available, > + new_opp->rate, new_opp->u_volt, new_opp->available); > + mutex_unlock(&dev_opp_list_lock); > + kfree(new_opp); > + return ret; > + } > + > list_add_rcu(&new_opp->node, head); > mutex_unlock(&dev_opp_list_lock); > > Otherwise, this looks fine to me.
On 20 May 2014 19:57, Nishanth Menon <nm@ti.com> wrote: >> + pr_warn("%s: duplicate OPPs detected. Existing: freq: %lu, volt: %lu, enabled: %d. New: freq: %lu, volt: %lu, enabled: %d\n", > dev_warn please? we already know the dev pointer. Also can we reduce > this down to 80 character limit if possible? breaking printk string into multiple line isn't suggested as it affects readability and so I kept it this way. Another was was to break printk itself intro two-three printk lines, but that would have looked bad on console. So, will retain it :( -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
On Tue, May 20, 2014 at 9:49 AM, Viresh Kumar <viresh.kumar@linaro.org> wrote: > > breaking printk string into multiple line isn't suggested as it affects > readability and so I kept it this way. Another was was to break printk > itself intro two-three printk lines, but that would have looked bad > on console. > > So, will retain it :( OK, dev_warn at least should be done.. we use dev_warn everywhere else. Regards, Nishanth Menon -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
On 20 May 2014 20:24, Nishanth Menon <nm@ti.com> wrote: > On Tue, May 20, 2014 at 9:49 AM, Viresh Kumar <viresh.kumar@linaro.org> wrote: >> >> breaking printk string into multiple line isn't suggested as it affects >> readability and so I kept it this way. Another was was to break printk >> itself intro two-three printk lines, but that would have looked bad >> on console. >> >> So, will retain it :( > OK, dev_warn at least should be done.. we use dev_warn everywhere else. Already done. :) TIP: One tip from my side :), Please use a blank line before and after your reply. It makes it much more readable. -- To unsubscribe from this list: send the line "unsubscribe linux-pm" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/drivers/base/power/opp.c b/drivers/base/power/opp.c index 2553867..cd9af42 100644 --- a/drivers/base/power/opp.c +++ b/drivers/base/power/opp.c @@ -389,6 +389,11 @@ EXPORT_SYMBOL_GPL(dev_pm_opp_find_freq_floor); * The opp is made available by default and it can be controlled using * dev_pm_opp_enable/disable functions. * + * Duplicate OPPs are discarded. Will return 0 if new OPP was duplicate of + * existing one (i.e. same freq and volt) and -EEXIST would be returned if new + * OPP had same freq but different volt as of an existing OPP OR if both were + * same but earlier OPP was disabled. + * * Locking: The internal device_opp and opp structures are RCU protected. * Hence this function internally uses RCU updater strategy with mutex locks * to keep the integrity of the internal data structures. Callers should ensure @@ -443,15 +448,31 @@ int dev_pm_opp_add(struct device *dev, unsigned long freq, unsigned long u_volt) new_opp->u_volt = u_volt; new_opp->available = true; - /* Insert new OPP in order of increasing frequency */ + /* + * Insert new OPP in order of increasing frequency + * and discard if already present + */ head = &dev_opp->opp_list; list_for_each_entry_rcu(opp, &dev_opp->opp_list, node) { - if (new_opp->rate < opp->rate) + if (new_opp->rate <= opp->rate) break; else head = &opp->node; } + /* Duplicate OPPs ? */ + if (new_opp->rate == opp->rate) { + int ret = (new_opp->u_volt == opp->u_volt) && opp->available ? + 0 : -EEXIST; + + pr_warn("%s: duplicate OPPs detected. Existing: freq: %lu, volt: %lu, enabled: %d. New: freq: %lu, volt: %lu, enabled: %d\n", + __func__, opp->rate, opp->u_volt, opp->available, + new_opp->rate, new_opp->u_volt, new_opp->available); + mutex_unlock(&dev_opp_list_lock); + kfree(new_opp); + return ret; + } + list_add_rcu(&new_opp->node, head); mutex_unlock(&dev_opp_list_lock);