linux-kernel - Re: [PATCH] cpufreq: remove sysfs link when a cpu != policy->cpu, is removed

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Message-ID: <1848612.IZFZXgfmHj@vostro.rjw.lan>
Date:	Mon, 17 Feb 2014 23:03:27 +0100
From:	"Rafael J. Wysocki" <rjw@...ysocki.net>
To:	Viresh Kumar <viresh.kumar@...aro.org>
Cc:	swarren@...dia.com, linaro-kernel@...ts.linaro.org,
	cpufreq@...r.kernel.org, linux-pm@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] cpufreq: remove sysfs link when a cpu != policy->cpu, is removed

On Monday, February 17, 2014 02:52:11 PM Viresh Kumar wrote:
> Earlier patch tried to do this but missed this piece of code to fix.
> 
> 42f921a cpufreq: remove sysfs files for CPUs which failed to come back after
> resume
> 
> Currently we are getting this on suspend/resume:
> 
> ------------[ cut here ]------------
> WARNING: CPU: 0 PID: 877 at fs/sysfs/dir.c:52 sysfs_warn_dup+0x68/0x84()
> sysfs: cannot create duplicate filename '/devices/system/cpu/cpu1/cpufreq'
> Modules linked in: brcmfmac brcmutil
> CPU: 0 PID: 877 Comm: test-rtc-resume Not tainted 3.14.0-rc2-00259-g9398a10cd964 #12
> [<c0015bac>] (unwind_backtrace) from [<c0011850>] (show_stack+0x10/0x14)
> [<c0011850>] (show_stack) from [<c056e018>] (dump_stack+0x80/0xcc)
> [<c056e018>] (dump_stack) from [<c0025e44>] (warn_slowpath_common+0x64/0x88)
> [<c0025e44>] (warn_slowpath_common) from [<c0025efc>] (warn_slowpath_fmt+0x30/0x40)
> [<c0025efc>] (warn_slowpath_fmt) from [<c012776c>] (sysfs_warn_dup+0x68/0x84)
> [<c012776c>] (sysfs_warn_dup) from [<c0127a54>] (sysfs_do_create_link_sd+0xb0/0xb8)
> [<c0127a54>] (sysfs_do_create_link_sd) from [<c038ef64>] (__cpufreq_add_dev.isra.27+0x2a8/0x814)
> [<c038ef64>] (__cpufreq_add_dev.isra.27) from [<c038f548>] (cpufreq_cpu_callback+0x70/0x8c)
> [<c038f548>] (cpufreq_cpu_callback) from [<c0043864>] (notifier_call_chain+0x44/0x84)
> [<c0043864>] (notifier_call_chain) from [<c0025f60>] (__cpu_notify+0x28/0x44)
> [<c0025f60>] (__cpu_notify) from [<c00261e8>] (_cpu_up+0xf0/0x140)
> [<c00261e8>] (_cpu_up) from [<c0569eb8>] (enable_nonboot_cpus+0x68/0xb0)
> [<c0569eb8>] (enable_nonboot_cpus) from [<c006339c>] (suspend_devices_and_enter+0x198/0x2dc)
> [<c006339c>] (suspend_devices_and_enter) from [<c0063654>] (pm_suspend+0x174/0x1e8)
> [<c0063654>] (pm_suspend) from [<c00624e0>] (state_store+0x6c/0xbc)
> [<c00624e0>] (state_store) from [<c01fc200>] (kobj_attr_store+0x14/0x20)
> [<c01fc200>] (kobj_attr_store) from [<c0126e50>] (sysfs_kf_write+0x44/0x48)
> [<c0126e50>] (sysfs_kf_write) from [<c012a274>] (kernfs_fop_write+0xb4/0x14c)
> [<c012a274>] (kernfs_fop_write) from [<c00d4818>] (vfs_write+0xa8/0x180)
> [<c00d4818>] (vfs_write) from [<c00d4bb8>] (SyS_write+0x3c/0x70)
> [<c00d4bb8>] (SyS_write) from [<c000e620>] (ret_fast_syscall+0x0/0x30)
> ---[ end trace 76969904b614c18f ]---
> 
> Fix this by removing sysfs link for cpufreq directory when cpu removed isn't
> policy->cpu.
> 
> Reported-by: Stephen Warren <swarren@...dia.com>
> Signed-off-by: Viresh Kumar <viresh.kumar@...aro.org>
> ---
> 
> Fix for 3.14 only.

Queued up for 3.14, thanks!

>  drivers/cpufreq/cpufreq.c | 3 +--
>  1 file changed, 1 insertion(+), 2 deletions(-)
> 
> diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
> index 08ca8c9..cb003a6 100644
> --- a/drivers/cpufreq/cpufreq.c
> +++ b/drivers/cpufreq/cpufreq.c
> @@ -1323,8 +1323,7 @@ static int __cpufreq_remove_dev_prepare(struct device *dev,
>  	up_read(&policy->rwsem);
>  
>  	if (cpu != policy->cpu) {
> -		if (!frozen)
> -			sysfs_remove_link(&dev->kobj, "cpufreq");
> +		sysfs_remove_link(&dev->kobj, "cpufreq");
>  	} else if (cpus > 1) {
>  		new_cpu = cpufreq_nominate_new_policy_cpu(policy, cpu);
>  		if (new_cpu >= 0) {
> 

-- 
I speak only for myself.
Rafael J. Wysocki, Intel Open Source Technology Center.
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