| Message ID | 20200831083832.17889-1-digetx@gmail.com (mailing list archive) |
|---|---|
| State | New, archived |
| Delegated to: | viresh kumar |
| Headers | show |
| Series | [RESEND,v4] cpuidle: tegra: Correctly handle result of arm_cpuidle_simple_enter() | expand |
31.08.2020 11:38, Dmitry Osipenko пишет: > The enter() callback of CPUIDLE drivers returns index of the entered idle > state on success or a negative value on failure. The negative value could > any negative value, i.e. it doesn't necessarily needs to be a error code. > That's because CPUIDLE core only cares about the fact of failure and not > about the reason of the enter() failure. > > Like every other enter() callback, the arm_cpuidle_simple_enter() returns > the entered idle-index on success. Unlike some of other drivers, it never > fails. It happened that TEGRA_C1=index=err=0 in the code of cpuidle-tegra > driver, and thus, there is no problem for the cpuidle-tegra driver created > by the typo in the code which assumes that the arm_cpuidle_simple_enter() > returns a error code. > > The arm_cpuidle_simple_enter() also may return a -ENODEV error if CPU_IDLE > is disabled in a kernel's config, but all CPUIDLE drivers are disabled if > CPU_IDLE is disabled, including the cpuidle-tegra driver. So we can't ever > see the error code from arm_cpuidle_simple_enter() today. > > Of course the code may get some changes in the future and then the > typo may transform into a real bug, so let's correct the typo! The > tegra_cpuidle_state_enter() is now changed to make it return the entered > idle-index on success and negative error code on fail, which puts it on > par with the arm_cpuidle_simple_enter(), making code consistent in regards > to the error handling. > > This patch fixes a minor typo in the code, it doesn't fix any bugs. > > Reviewed-by: Jon Hunter <jonathanh@nvidia.com> > Signed-off-by: Dmitry Osipenko <digetx@gmail.com> > --- Hello, Daniel! Pinging you just in a case if this patch slipped away from you :)
On Mon, Aug 31, 2020 at 10:39 AM Dmitry Osipenko <digetx@gmail.com> wrote: > > The enter() callback of CPUIDLE drivers returns index of the entered idle > state on success or a negative value on failure. The negative value could > any negative value, i.e. it doesn't necessarily needs to be a error code. > That's because CPUIDLE core only cares about the fact of failure and not > about the reason of the enter() failure. > > Like every other enter() callback, the arm_cpuidle_simple_enter() returns > the entered idle-index on success. Unlike some of other drivers, it never > fails. It happened that TEGRA_C1=index=err=0 in the code of cpuidle-tegra > driver, and thus, there is no problem for the cpuidle-tegra driver created > by the typo in the code which assumes that the arm_cpuidle_simple_enter() > returns a error code. > > The arm_cpuidle_simple_enter() also may return a -ENODEV error if CPU_IDLE > is disabled in a kernel's config, but all CPUIDLE drivers are disabled if > CPU_IDLE is disabled, including the cpuidle-tegra driver. So we can't ever > see the error code from arm_cpuidle_simple_enter() today. > > Of course the code may get some changes in the future and then the > typo may transform into a real bug, so let's correct the typo! The > tegra_cpuidle_state_enter() is now changed to make it return the entered > idle-index on success and negative error code on fail, which puts it on > par with the arm_cpuidle_simple_enter(), making code consistent in regards > to the error handling. > > This patch fixes a minor typo in the code, it doesn't fix any bugs. > > Reviewed-by: Jon Hunter <jonathanh@nvidia.com> > Signed-off-by: Dmitry Osipenko <digetx@gmail.com> Applied as 5.10 material, thanks! > --- > > Changelog: > > v4: No code changes. Added r-b from Jon Hunter and re-sending for 5.10. > > v3: The tegra_cpuidle_state_enter() now returns entered idle-index on > success instead of 0. Hence the error message will be shown by the > tegra-cpuidle driver if arm_cpuidle_simple_enter() will ever fail. > Again thanks to Jon Hunter! > > v2: Improved commit message by clarifying what values are returned by > arm_cpuidle_simple_enter() and when. Thanks to Jon Hunter for the > suggestion! > > drivers/cpuidle/cpuidle-tegra.c | 34 +++++++++++++++++++-------------- > 1 file changed, 20 insertions(+), 14 deletions(-) > > diff --git a/drivers/cpuidle/cpuidle-tegra.c b/drivers/cpuidle/cpuidle-tegra.c > index a12fb141875a..e8956706a291 100644 > --- a/drivers/cpuidle/cpuidle-tegra.c > +++ b/drivers/cpuidle/cpuidle-tegra.c > @@ -172,7 +172,7 @@ static int tegra_cpuidle_coupled_barrier(struct cpuidle_device *dev) > static int tegra_cpuidle_state_enter(struct cpuidle_device *dev, > int index, unsigned int cpu) > { > - int ret; > + int err; > > /* > * CC6 state is the "CPU cluster power-off" state. In order to > @@ -183,9 +183,9 @@ static int tegra_cpuidle_state_enter(struct cpuidle_device *dev, > * CPU cores, GIC and L2 cache). > */ > if (index == TEGRA_CC6) { > - ret = tegra_cpuidle_coupled_barrier(dev); > - if (ret) > - return ret; > + err = tegra_cpuidle_coupled_barrier(dev); > + if (err) > + return err; > } > > local_fiq_disable(); > @@ -194,15 +194,15 @@ static int tegra_cpuidle_state_enter(struct cpuidle_device *dev, > > switch (index) { > case TEGRA_C7: > - ret = tegra_cpuidle_c7_enter(); > + err = tegra_cpuidle_c7_enter(); > break; > > case TEGRA_CC6: > - ret = tegra_cpuidle_cc6_enter(cpu); > + err = tegra_cpuidle_cc6_enter(cpu); > break; > > default: > - ret = -EINVAL; > + err = -EINVAL; > break; > } > > @@ -210,7 +210,7 @@ static int tegra_cpuidle_state_enter(struct cpuidle_device *dev, > tegra_pm_clear_cpu_in_lp2(); > local_fiq_enable(); > > - return ret; > + return err ?: index; > } > > static int tegra_cpuidle_adjust_state_index(int index, unsigned int cpu) > @@ -236,21 +236,27 @@ static int tegra_cpuidle_enter(struct cpuidle_device *dev, > int index) > { > unsigned int cpu = cpu_logical_map(dev->cpu); > - int err; > + int ret; > > index = tegra_cpuidle_adjust_state_index(index, cpu); > if (dev->states_usage[index].disable) > return -1; > > if (index == TEGRA_C1) > - err = arm_cpuidle_simple_enter(dev, drv, index); > + ret = arm_cpuidle_simple_enter(dev, drv, index); > else > - err = tegra_cpuidle_state_enter(dev, index, cpu); > + ret = tegra_cpuidle_state_enter(dev, index, cpu); > > - if (err && (err != -EINTR || index != TEGRA_CC6)) > - pr_err_once("failed to enter state %d err: %d\n", index, err); > + if (ret < 0) { > + if (ret != -EINTR || index != TEGRA_CC6) > + pr_err_once("failed to enter state %d err: %d\n", > + index, ret); > + index = -1; > + } else { > + index = ret; > + } > > - return err ? -1 : index; > + return index; > } > > static int tegra114_enter_s2idle(struct cpuidle_device *dev, > -- > 2.27.0 >
diff --git a/drivers/cpuidle/cpuidle-tegra.c b/drivers/cpuidle/cpuidle-tegra.c index a12fb141875a..e8956706a291 100644 --- a/drivers/cpuidle/cpuidle-tegra.c +++ b/drivers/cpuidle/cpuidle-tegra.c @@ -172,7 +172,7 @@ static int tegra_cpuidle_coupled_barrier(struct cpuidle_device *dev) static int tegra_cpuidle_state_enter(struct cpuidle_device *dev, int index, unsigned int cpu) { - int ret; + int err; /* * CC6 state is the "CPU cluster power-off" state. In order to @@ -183,9 +183,9 @@ static int tegra_cpuidle_state_enter(struct cpuidle_device *dev, * CPU cores, GIC and L2 cache). */ if (index == TEGRA_CC6) { - ret = tegra_cpuidle_coupled_barrier(dev); - if (ret) - return ret; + err = tegra_cpuidle_coupled_barrier(dev); + if (err) + return err; } local_fiq_disable(); @@ -194,15 +194,15 @@ static int tegra_cpuidle_state_enter(struct cpuidle_device *dev, switch (index) { case TEGRA_C7: - ret = tegra_cpuidle_c7_enter(); + err = tegra_cpuidle_c7_enter(); break; case TEGRA_CC6: - ret = tegra_cpuidle_cc6_enter(cpu); + err = tegra_cpuidle_cc6_enter(cpu); break; default: - ret = -EINVAL; + err = -EINVAL; break; } @@ -210,7 +210,7 @@ static int tegra_cpuidle_state_enter(struct cpuidle_device *dev, tegra_pm_clear_cpu_in_lp2(); local_fiq_enable(); - return ret; + return err ?: index; } static int tegra_cpuidle_adjust_state_index(int index, unsigned int cpu) @@ -236,21 +236,27 @@ static int tegra_cpuidle_enter(struct cpuidle_device *dev, int index) { unsigned int cpu = cpu_logical_map(dev->cpu); - int err; + int ret; index = tegra_cpuidle_adjust_state_index(index, cpu); if (dev->states_usage[index].disable) return -1; if (index == TEGRA_C1) - err = arm_cpuidle_simple_enter(dev, drv, index); + ret = arm_cpuidle_simple_enter(dev, drv, index); else - err = tegra_cpuidle_state_enter(dev, index, cpu); + ret = tegra_cpuidle_state_enter(dev, index, cpu); - if (err && (err != -EINTR || index != TEGRA_CC6)) - pr_err_once("failed to enter state %d err: %d\n", index, err); + if (ret < 0) { + if (ret != -EINTR || index != TEGRA_CC6) + pr_err_once("failed to enter state %d err: %d\n", + index, ret); + index = -1; + } else { + index = ret; + } - return err ? -1 : index; + return index; } static int tegra114_enter_s2idle(struct cpuidle_device *dev,