| Message ID | 1469191370-1285-1-git-send-email-jszhang@marvell.com (mailing list archive) |
|---|---|
| State | Not Applicable, archived |
| Headers | show |
Hi,
[auto build test WARNING on pm/linux-next]
[also build test WARNING on v4.7-rc7 next-20160722]
[if your patch is applied to the wrong git tree, please drop us a note to help improve the system]
url: https://github.com/0day-ci/linux/commits/Jisheng-Zhang/PM-OPP-optimize-dev_pm_opp_set_rate-a-bit/20160722-205339
base: https://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm.git linux-next
config: x86_64-allmodconfig (attached as .config)
compiler: gcc-6 (Debian 6.1.1-9) 6.1.1 20160705
reproduce:
# save the attached .config to linux build tree
make ARCH=x86_64
Note: it may well be a FALSE warning. FWIW you are at least aware of it now.
http://gcc.gnu.org/wiki/Better_Uninitialized_Warnings
All warnings (new ones prefixed by >>):
drivers/base/power/opp/core.c: In function 'dev_pm_opp_set_rate':
>> drivers/base/power/opp/core.c:666:3: warning: 'ou_volt_max' may be used uninitialized in this function [-Wmaybe-uninitialized]
_set_opp_voltage(dev, reg, ou_volt, ou_volt_min, ou_volt_max);
^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>> drivers/base/power/opp/core.c:666:3: warning: 'ou_volt_min' may be used uninitialized in this function [-Wmaybe-uninitialized]
>> drivers/base/power/opp/core.c:666:3: warning: 'ou_volt' may be used uninitialized in this function [-Wmaybe-uninitialized]
vim +/ou_volt_max +666 drivers/base/power/opp/core.c
6a0712f6 drivers/base/power/opp/core.c Viresh Kumar 2016-02-09 650 if (freq < old_freq) {
6a0712f6 drivers/base/power/opp/core.c Viresh Kumar 2016-02-09 651 ret = _set_opp_voltage(dev, reg, u_volt, u_volt_min,
6a0712f6 drivers/base/power/opp/core.c Viresh Kumar 2016-02-09 652 u_volt_max);
6a0712f6 drivers/base/power/opp/core.c Viresh Kumar 2016-02-09 653 if (ret)
6a0712f6 drivers/base/power/opp/core.c Viresh Kumar 2016-02-09 654 goto restore_freq;
6a0712f6 drivers/base/power/opp/core.c Viresh Kumar 2016-02-09 655 }
6a0712f6 drivers/base/power/opp/core.c Viresh Kumar 2016-02-09 656
6a0712f6 drivers/base/power/opp/core.c Viresh Kumar 2016-02-09 657 return 0;
6a0712f6 drivers/base/power/opp/core.c Viresh Kumar 2016-02-09 658
6a0712f6 drivers/base/power/opp/core.c Viresh Kumar 2016-02-09 659 restore_freq:
6a0712f6 drivers/base/power/opp/core.c Viresh Kumar 2016-02-09 660 if (clk_set_rate(clk, old_freq))
6a0712f6 drivers/base/power/opp/core.c Viresh Kumar 2016-02-09 661 dev_err(dev, "%s: failed to restore old-freq (%lu Hz)\n",
6a0712f6 drivers/base/power/opp/core.c Viresh Kumar 2016-02-09 662 __func__, old_freq);
6a0712f6 drivers/base/power/opp/core.c Viresh Kumar 2016-02-09 663 restore_voltage:
6a0712f6 drivers/base/power/opp/core.c Viresh Kumar 2016-02-09 664 /* This shouldn't harm even if the voltages weren't updated earlier */
6a0712f6 drivers/base/power/opp/core.c Viresh Kumar 2016-02-09 665 if (!IS_ERR(old_opp))
6a0712f6 drivers/base/power/opp/core.c Viresh Kumar 2016-02-09 @666 _set_opp_voltage(dev, reg, ou_volt, ou_volt_min, ou_volt_max);
6a0712f6 drivers/base/power/opp/core.c Viresh Kumar 2016-02-09 667
6a0712f6 drivers/base/power/opp/core.c Viresh Kumar 2016-02-09 668 return ret;
6a0712f6 drivers/base/power/opp/core.c Viresh Kumar 2016-02-09 669 }
6a0712f6 drivers/base/power/opp/core.c Viresh Kumar 2016-02-09 670 EXPORT_SYMBOL_GPL(dev_pm_opp_set_rate);
6a0712f6 drivers/base/power/opp/core.c Viresh Kumar 2016-02-09 671
2c2709dc drivers/base/power/opp/core.c Viresh Kumar 2016-02-16 672 /* OPP-dev Helpers */
2c2709dc drivers/base/power/opp/core.c Viresh Kumar 2016-02-16 673 static void _kfree_opp_dev_rcu(struct rcu_head *head)
06441658 drivers/base/power/opp.c Viresh Kumar 2015-07-29 674 {
:::::: The code at line 666 was first introduced by commit
:::::: 6a0712f6f199e737aa5913d28ec4bd3a25de9660 PM / OPP: Add dev_pm_opp_set_rate()
:::::: TO: Viresh Kumar <viresh.kumar@linaro.org>
:::::: CC: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
---
0-DAY kernel test infrastructure Open Source Technology Center
https://lists.01.org/pipermail/kbuild-all Intel Corporation
On 22-07-16, 20:42, Jisheng Zhang wrote: > static int _set_opp_voltage(struct device *dev, struct regulator *reg, > unsigned long u_volt, unsigned long u_volt_min, > unsigned long u_volt_max) > @@ -586,9 +565,24 @@ int dev_pm_opp_set_rate(struct device *dev, unsigned long target_freq) > return -EINVAL; > } > > - clk = _get_opp_clk(dev); > - if (IS_ERR(clk)) > + rcu_read_lock(); > + > + opp_table = _find_opp_table(dev); > + if (IS_ERR(opp_table)) { > + dev_err(dev, "%s: device opp doesn't exist\n", __func__); > + rcu_read_unlock(); > + return PTR_ERR(opp_table); > + } > + > + clk = opp_table->clk; > + if (IS_ERR(clk)) { > + dev_err(dev, "%s: No clock available for the device\n", > + __func__); > + rcu_read_unlock(); > return PTR_ERR(clk); > + } > + > + rcu_read_unlock(); It is not _safe_ to use opp_table pointer after the rcu_read_unlock() here.
Dear Viresh, On Fri, 22 Jul 2016 09:21:51 -0700 Viresh Kumar wrote: > On 22-07-16, 20:42, Jisheng Zhang wrote: > > static int _set_opp_voltage(struct device *dev, struct regulator *reg, > > unsigned long u_volt, unsigned long u_volt_min, > > unsigned long u_volt_max) > > @@ -586,9 +565,24 @@ int dev_pm_opp_set_rate(struct device *dev, unsigned long target_freq) > > return -EINVAL; > > } > > > > - clk = _get_opp_clk(dev); > > - if (IS_ERR(clk)) > > + rcu_read_lock(); > > + > > + opp_table = _find_opp_table(dev); > > + if (IS_ERR(opp_table)) { > > + dev_err(dev, "%s: device opp doesn't exist\n", __func__); > > + rcu_read_unlock(); > > + return PTR_ERR(opp_table); > > + } > > + > > + clk = opp_table->clk; > > + if (IS_ERR(clk)) { > > + dev_err(dev, "%s: No clock available for the device\n", > > + __func__); > > + rcu_read_unlock(); > > return PTR_ERR(clk); > > + } > > + > > + rcu_read_unlock(); > > It is not _safe_ to use opp_table pointer after the rcu_read_unlock() Oops, indeed. Thanks very much for pointing it out! Will fix it in v2, so it seems we can only reduce the call of _find_opp_table to twice. Thanks, Jisheng -- 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
Dear all, On Fri, 22 Jul 2016 22:30:53 +0800 kbuild test robot wrote: > Hi, > > [auto build test WARNING on pm/linux-next] > [also build test WARNING on v4.7-rc7 next-20160722] > [if your patch is applied to the wrong git tree, please drop us a note to help improve the system] > > url: https://github.com/0day-ci/linux/commits/Jisheng-Zhang/PM-OPP-optimize-dev_pm_opp_set_rate-a-bit/20160722-205339 > base: https://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm.git linux-next > config: x86_64-allmodconfig (attached as .config) > compiler: gcc-6 (Debian 6.1.1-9) 6.1.1 20160705 > reproduce: > # save the attached .config to linux build tree > make ARCH=x86_64 > > Note: it may well be a FALSE warning. FWIW you are at least aware of it now. > http://gcc.gnu.org/wiki/Better_Uninitialized_Warnings > > All warnings (new ones prefixed by >>): > > drivers/base/power/opp/core.c: In function 'dev_pm_opp_set_rate': > >> drivers/base/power/opp/core.c:666:3: warning: 'ou_volt_max' may be used uninitialized in this function [-Wmaybe-uninitialized] > _set_opp_voltage(dev, reg, ou_volt, ou_volt_min, ou_volt_max); > ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ > >> drivers/base/power/opp/core.c:666:3: warning: 'ou_volt_min' may be used uninitialized in this function [-Wmaybe-uninitialized] > >> drivers/base/power/opp/core.c:666:3: warning: 'ou_volt' may be used uninitialized in this function [-Wmaybe-uninitialized] These warnings seem weired. We only use them when !IS_ERR(old_opp), and we should already set them if !IS_ERR(old_opp). Another weired thing is if we add something, printk e.g in _find_freq_ceil(), then these warnings disappear Could you please kindly give some suggestions about how to fix these warnings? Thanks, Jisheng > > vim +/ou_volt_max +666 drivers/base/power/opp/core.c > > 6a0712f6 drivers/base/power/opp/core.c Viresh Kumar 2016-02-09 650 if (freq < old_freq) { > 6a0712f6 drivers/base/power/opp/core.c Viresh Kumar 2016-02-09 651 ret = _set_opp_voltage(dev, reg, u_volt, u_volt_min, > 6a0712f6 drivers/base/power/opp/core.c Viresh Kumar 2016-02-09 652 u_volt_max); > 6a0712f6 drivers/base/power/opp/core.c Viresh Kumar 2016-02-09 653 if (ret) > 6a0712f6 drivers/base/power/opp/core.c Viresh Kumar 2016-02-09 654 goto restore_freq; > 6a0712f6 drivers/base/power/opp/core.c Viresh Kumar 2016-02-09 655 } > 6a0712f6 drivers/base/power/opp/core.c Viresh Kumar 2016-02-09 656 > 6a0712f6 drivers/base/power/opp/core.c Viresh Kumar 2016-02-09 657 return 0; > 6a0712f6 drivers/base/power/opp/core.c Viresh Kumar 2016-02-09 658 > 6a0712f6 drivers/base/power/opp/core.c Viresh Kumar 2016-02-09 659 restore_freq: > 6a0712f6 drivers/base/power/opp/core.c Viresh Kumar 2016-02-09 660 if (clk_set_rate(clk, old_freq)) > 6a0712f6 drivers/base/power/opp/core.c Viresh Kumar 2016-02-09 661 dev_err(dev, "%s: failed to restore old-freq (%lu Hz)\n", > 6a0712f6 drivers/base/power/opp/core.c Viresh Kumar 2016-02-09 662 __func__, old_freq); > 6a0712f6 drivers/base/power/opp/core.c Viresh Kumar 2016-02-09 663 restore_voltage: > 6a0712f6 drivers/base/power/opp/core.c Viresh Kumar 2016-02-09 664 /* This shouldn't harm even if the voltages weren't updated earlier */ > 6a0712f6 drivers/base/power/opp/core.c Viresh Kumar 2016-02-09 665 if (!IS_ERR(old_opp)) > 6a0712f6 drivers/base/power/opp/core.c Viresh Kumar 2016-02-09 @666 _set_opp_voltage(dev, reg, ou_volt, ou_volt_min, ou_volt_max); > 6a0712f6 drivers/base/power/opp/core.c Viresh Kumar 2016-02-09 667 > 6a0712f6 drivers/base/power/opp/core.c Viresh Kumar 2016-02-09 668 return ret; > 6a0712f6 drivers/base/power/opp/core.c Viresh Kumar 2016-02-09 669 } > 6a0712f6 drivers/base/power/opp/core.c Viresh Kumar 2016-02-09 670 EXPORT_SYMBOL_GPL(dev_pm_opp_set_rate); > 6a0712f6 drivers/base/power/opp/core.c Viresh Kumar 2016-02-09 671 > 2c2709dc drivers/base/power/opp/core.c Viresh Kumar 2016-02-16 672 /* OPP-dev Helpers */ > 2c2709dc drivers/base/power/opp/core.c Viresh Kumar 2016-02-16 673 static void _kfree_opp_dev_rcu(struct rcu_head *head) > 06441658 drivers/base/power/opp.c Viresh Kumar 2015-07-29 674 { > > :::::: The code at line 666 was first introduced by commit > :::::: 6a0712f6f199e737aa5913d28ec4bd3a25de9660 PM / OPP: Add dev_pm_opp_set_rate() > > :::::: TO: Viresh Kumar <viresh.kumar@linaro.org> > :::::: CC: Rafael J. Wysocki <rafael.j.wysocki@intel.com> > > --- > 0-DAY kernel test infrastructure Open Source Technology Center > https://lists.01.org/pipermail/kbuild-all Intel Corporation -- 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
On Mon, 25 Jul 2016 13:19:47 +0800 Jisheng Zhang wrote: > Dear all, > > On Fri, 22 Jul 2016 22:30:53 +0800 kbuild test robot wrote: > > > Hi, > > > > [auto build test WARNING on pm/linux-next] > > [also build test WARNING on v4.7-rc7 next-20160722] > > [if your patch is applied to the wrong git tree, please drop us a note to help improve the system] > > > > url: https://github.com/0day-ci/linux/commits/Jisheng-Zhang/PM-OPP-optimize-dev_pm_opp_set_rate-a-bit/20160722-205339 > > base: https://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm.git linux-next > > config: x86_64-allmodconfig (attached as .config) > > compiler: gcc-6 (Debian 6.1.1-9) 6.1.1 20160705 > > reproduce: > > # save the attached .config to linux build tree > > make ARCH=x86_64 > > > > Note: it may well be a FALSE warning. FWIW you are at least aware of it now. > > http://gcc.gnu.org/wiki/Better_Uninitialized_Warnings > > > > All warnings (new ones prefixed by >>): > > > > drivers/base/power/opp/core.c: In function 'dev_pm_opp_set_rate': > > >> drivers/base/power/opp/core.c:666:3: warning: 'ou_volt_max' may be used uninitialized in this function [-Wmaybe-uninitialized] > > _set_opp_voltage(dev, reg, ou_volt, ou_volt_min, ou_volt_max); > > ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ > > >> drivers/base/power/opp/core.c:666:3: warning: 'ou_volt_min' may be used uninitialized in this function [-Wmaybe-uninitialized] > > >> drivers/base/power/opp/core.c:666:3: warning: 'ou_volt' may be used uninitialized in this function [-Wmaybe-uninitialized] > > These warnings seem weired. We only use them when !IS_ERR(old_opp), and we > should already set them if !IS_ERR(old_opp). Another weired thing is if > we add something, printk e.g in _find_freq_ceil(), then these warnings disappear Hmm, it looks that gcc will inline _find_freq_ceil(), then gcc can't detect that ou_volt* are already set. Mark _find_freq_ceil() noinline would fix the warnings Thanks, Jisheng > > Could you please kindly give some suggestions about how to fix these warnings? > -- 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/core.c b/drivers/base/power/opp/core.c index 7c04c87..96043ee 100644 --- a/drivers/base/power/opp/core.c +++ b/drivers/base/power/opp/core.c @@ -402,6 +402,22 @@ struct dev_pm_opp *dev_pm_opp_find_freq_exact(struct device *dev, } EXPORT_SYMBOL_GPL(dev_pm_opp_find_freq_exact); +static struct dev_pm_opp *_find_freq_ceil(struct opp_table *opp_table, + unsigned long *freq) +{ + struct dev_pm_opp *temp_opp, *opp = ERR_PTR(-ERANGE); + + list_for_each_entry_rcu(temp_opp, &opp_table->opp_list, node) { + if (temp_opp->available && temp_opp->rate >= *freq) { + opp = temp_opp; + *freq = opp->rate; + break; + } + } + + return opp; +} + /** * dev_pm_opp_find_freq_ceil() - Search for an rounded ceil freq * @dev: device for which we do this operation @@ -427,7 +443,6 @@ struct dev_pm_opp *dev_pm_opp_find_freq_ceil(struct device *dev, unsigned long *freq) { struct opp_table *opp_table; - struct dev_pm_opp *temp_opp, *opp = ERR_PTR(-ERANGE); opp_rcu_lockdep_assert(); @@ -440,15 +455,7 @@ struct dev_pm_opp *dev_pm_opp_find_freq_ceil(struct device *dev, if (IS_ERR(opp_table)) return ERR_CAST(opp_table); - list_for_each_entry_rcu(temp_opp, &opp_table->opp_list, node) { - if (temp_opp->available && temp_opp->rate >= *freq) { - opp = temp_opp; - *freq = opp->rate; - break; - } - } - - return opp; + return _find_freq_ceil(opp_table, freq); } EXPORT_SYMBOL_GPL(dev_pm_opp_find_freq_ceil); @@ -506,34 +513,6 @@ struct dev_pm_opp *dev_pm_opp_find_freq_floor(struct device *dev, } EXPORT_SYMBOL_GPL(dev_pm_opp_find_freq_floor); -/* - * The caller needs to ensure that opp_table (and hence the clk) isn't freed, - * while clk returned here is used. - */ -static struct clk *_get_opp_clk(struct device *dev) -{ - struct opp_table *opp_table; - struct clk *clk; - - rcu_read_lock(); - - opp_table = _find_opp_table(dev); - if (IS_ERR(opp_table)) { - dev_err(dev, "%s: device opp doesn't exist\n", __func__); - clk = ERR_CAST(opp_table); - goto unlock; - } - - clk = opp_table->clk; - if (IS_ERR(clk)) - dev_err(dev, "%s: No clock available for the device\n", - __func__); - -unlock: - rcu_read_unlock(); - return clk; -} - static int _set_opp_voltage(struct device *dev, struct regulator *reg, unsigned long u_volt, unsigned long u_volt_min, unsigned long u_volt_max) @@ -586,9 +565,24 @@ int dev_pm_opp_set_rate(struct device *dev, unsigned long target_freq) return -EINVAL; } - clk = _get_opp_clk(dev); - if (IS_ERR(clk)) + rcu_read_lock(); + + opp_table = _find_opp_table(dev); + if (IS_ERR(opp_table)) { + dev_err(dev, "%s: device opp doesn't exist\n", __func__); + rcu_read_unlock(); + return PTR_ERR(opp_table); + } + + clk = opp_table->clk; + if (IS_ERR(clk)) { + dev_err(dev, "%s: No clock available for the device\n", + __func__); + rcu_read_unlock(); return PTR_ERR(clk); + } + + rcu_read_unlock(); freq = clk_round_rate(clk, target_freq); if ((long)freq <= 0) @@ -605,14 +599,7 @@ int dev_pm_opp_set_rate(struct device *dev, unsigned long target_freq) rcu_read_lock(); - opp_table = _find_opp_table(dev); - if (IS_ERR(opp_table)) { - dev_err(dev, "%s: device opp doesn't exist\n", __func__); - rcu_read_unlock(); - return PTR_ERR(opp_table); - } - - old_opp = dev_pm_opp_find_freq_ceil(dev, &old_freq); + old_opp = _find_freq_ceil(opp_table, &old_freq); if (!IS_ERR(old_opp)) { ou_volt = old_opp->u_volt; ou_volt_min = old_opp->u_volt_min; @@ -622,7 +609,7 @@ int dev_pm_opp_set_rate(struct device *dev, unsigned long target_freq) __func__, old_freq, PTR_ERR(old_opp)); } - opp = dev_pm_opp_find_freq_ceil(dev, &freq); + opp = _find_freq_ceil(opp_table, &freq); if (IS_ERR(opp)) { ret = PTR_ERR(opp); dev_err(dev, "%s: failed to find OPP for freq %lu (%d)\n",
In dev_pm_opp_set_rate(), _find_opp_table() is called three times: once by _get_opp_clk(), twice by dev_pm_opp_find_freq_ceil(). If there are several opp_tables in the system, three times of opp table finding is a big waste. This patch reduced the call of _find_opp_table() to only once. Signed-off-by: Jisheng Zhang <jszhang@marvell.com> --- drivers/base/power/opp/core.c | 85 ++++++++++++++++++------------------------- 1 file changed, 36 insertions(+), 49 deletions(-)