Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > linux.kernel > #1554770 > unrolled thread

Re: [PATCH 12/12] PM / OPP: Update Documentation to remove RCU specific bits

Back to article view | Back to linux.kernel

This discussion starts older than the indexed window; earlier articles aren't shown. The article labeled Started by below is the oldest one visible, not the original post.

Contents

  Re: [PATCH 12/12] PM / OPP: Update Documentation to remove RCU  specific bits Stephen Boyd <sboyd@codeaurora.org> - 2017-01-09 23:40 +0100
    Re: [PATCH 12/12] PM / OPP: Update Documentation to remove RCU  specific bits Viresh Kumar <viresh.kumar@linaro.org> - 2017-01-10 05:40 +0100
      Re: [PATCH 12/12] PM / OPP: Update Documentation to remove RCU  specific bits Stephen Boyd <sboyd@codeaurora.org> - 2017-01-13 09:50 +0100

#1554770 — Re: [PATCH 12/12] PM / OPP: Update Documentation to remove RCU specific bits

On 12/07, Viresh Kumar wrote:
> @@ -137,15 +121,18 @@ functions return the matching pointer representing the opp if a match is
>  found, else returns error. These errors are expected to be handled by standard
>  error checks such as IS_ERR() and appropriate actions taken by the caller.
>  
> +Callers of these functions shall call dev_pm_opp_put() after they have used the
> +OPP. Otherwise the memory for the OPP will never get freed and result in
> +memleak.
> +
>  dev_pm_opp_find_freq_exact - Search for an OPP based on an *exact* frequency and
>  	availability. This function is especially useful to enable an OPP which
>  	is not available by default.
>  	Example: In a case when SoC framework detects a situation where a
>  	higher frequency could be made available, it can use this function to
>  	find the OPP prior to call the dev_pm_opp_enable to actually make it available.
> -	 rcu_read_lock();
>  	 opp = dev_pm_opp_find_freq_exact(dev, 1000000000, false);
> -	 rcu_read_unlock();
> +	 dev_pm_opp_put(opp);
>  	 /* dont operate on the pointer.. just do a sanity check.. */
>  	 if (IS_ERR(opp)) {
>  		pr_err("frequency not disabled!\n");
> @@ -163,9 +150,8 @@ dev_pm_opp_find_freq_floor - Search for an available OPP which is *at most* the
>  	frequency.
>  	Example: To find the highest opp for a device:
>  	 freq = ULONG_MAX;
> -	 rcu_read_lock();
>  	 dev_pm_opp_find_freq_floor(dev, &freq);
> -	 rcu_read_unlock();
> +	 dev_pm_opp_put(opp);

opp doesn't exist in the scope here. Missing an assignment during
the dev_pm_opp_find_freq_floor() call?

-- 
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum,
a Linux Foundation Collaborative Project

[toc] | [next] | [standalone]

#1554917

On 09-01-17, 14:39, Stephen Boyd wrote:
> On 12/07, Viresh Kumar wrote:
> > @@ -137,15 +121,18 @@ functions return the matching pointer representing the opp if a match is
> >  found, else returns error. These errors are expected to be handled by standard
> >  error checks such as IS_ERR() and appropriate actions taken by the caller.
> >  
> > +Callers of these functions shall call dev_pm_opp_put() after they have used the
> > +OPP. Otherwise the memory for the OPP will never get freed and result in
> > +memleak.
> > +
> >  dev_pm_opp_find_freq_exact - Search for an OPP based on an *exact* frequency and
> >  	availability. This function is especially useful to enable an OPP which
> >  	is not available by default.
> >  	Example: In a case when SoC framework detects a situation where a
> >  	higher frequency could be made available, it can use this function to
> >  	find the OPP prior to call the dev_pm_opp_enable to actually make it available.
> > -	 rcu_read_lock();
> >  	 opp = dev_pm_opp_find_freq_exact(dev, 1000000000, false);
> > -	 rcu_read_unlock();
> > +	 dev_pm_opp_put(opp);
> >  	 /* dont operate on the pointer.. just do a sanity check.. */
> >  	 if (IS_ERR(opp)) {
> >  		pr_err("frequency not disabled!\n");
> > @@ -163,9 +150,8 @@ dev_pm_opp_find_freq_floor - Search for an available OPP which is *at most* the
> >  	frequency.
> >  	Example: To find the highest opp for a device:
> >  	 freq = ULONG_MAX;
> > -	 rcu_read_lock();
> >  	 dev_pm_opp_find_freq_floor(dev, &freq);
> > -	 rcu_read_unlock();
> > +	 dev_pm_opp_put(opp);
> 
> opp doesn't exist in the scope here. Missing an assignment during
> the dev_pm_opp_find_freq_floor() call?

Thanks for noticing this. Following is the diff I am adding to this patch:

diff --git a/Documentation/power/opp.txt b/Documentation/power/opp.txt
index be895e32022d..0c007e250cd1 100644
--- a/Documentation/power/opp.txt
+++ b/Documentation/power/opp.txt
@@ -150,7 +150,7 @@ dev_pm_opp_find_freq_floor - Search for an available OPP which is *at most* the
        frequency.
        Example: To find the highest opp for a device:
         freq = ULONG_MAX;
-        dev_pm_opp_find_freq_floor(dev, &freq);
+        opp = dev_pm_opp_find_freq_floor(dev, &freq);
         dev_pm_opp_put(opp);
 
 dev_pm_opp_find_freq_ceil - Search for an available OPP which is *at least* the
@@ -159,7 +159,7 @@ dev_pm_opp_find_freq_ceil - Search for an available OPP which is *at least* the
        frequency.
        Example 1: To find the lowest opp for a device:
         freq = 0;
-        dev_pm_opp_find_freq_ceil(dev, &freq);
+        opp = dev_pm_opp_find_freq_ceil(dev, &freq);
         dev_pm_opp_put(opp);
        Example 2: A simplified implementation of a SoC cpufreq_driver->target:
         soc_cpufreq_target(..)
@@ -252,6 +252,7 @@ dev_pm_opp_get_freq - Retrieve the freq represented by the opp pointer.
                 if (!IS_ERR(max_opp) && !IS_ERR(requested_opp))
                        r = soc_test_validity(max_opp, requested_opp);
                 dev_pm_opp_put(max_opp);
+                dev_pm_opp_put(requested_opp);
                /* do other things */
         }
         soc_test_validity(..)


Please add your RBY if it looks fine to you now.

-- 
viresh

[toc] | [prev] | [next] | [standalone]

#1558115

On 01/10, Viresh Kumar wrote:
> @@ -252,6 +252,7 @@ dev_pm_opp_get_freq - Retrieve the freq represented by the opp pointer.
>                  if (!IS_ERR(max_opp) && !IS_ERR(requested_opp))
>                         r = soc_test_validity(max_opp, requested_opp);
>                  dev_pm_opp_put(max_opp);
> +                dev_pm_opp_put(requested_opp);
>                 /* do other things */
>          }
>          soc_test_validity(..)
> 
> 
> Please add your RBY if it looks fine to you now.
> 

Sure.

Reviewed-by: Stephen Boyd <sboyd@codeaurora.org>

-- 
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum,
a Linux Foundation Collaborative Project

[toc] | [prev] | [standalone]

Back to top | Article view | linux.kernel

csiph-web