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Merge branch 'for-3.6-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq

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Pull workqueue / powernow-k8 fix from Tejun Heo:
 "This is the fix for the bug where cpufreq/powernow-k8 was tripping
  BUG_ON() in try_to_wake_up_local() by migrating workqueue worker to a
  different CPU.

    https://bugzilla.kernel.org/show_bug.cgi?id=47301

  As discussed, the fix is now two parts - one to reimplement
  work_on_cpu() so that it doesn't create a new kthread each time and
  the actual fix which makes powernow-k8 use work_on_cpu() instead of
  performing manual migration.

  While pretty late in the merge cycle, both changes are on the safer
  side.  Jiri and I verified two existing users of work_on_cpu() and
  Duncan confirmed that the powernow-k8 fix survived about 18 hours of
  testing."

* 'for-3.6-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq:
  cpufreq/powernow-k8: workqueue user shouldn't migrate the kworker to another CPU
  workqueue: reimplement work_on_cpu() using system_wq
This commit is contained in:
Linus Torvalds 2012-09-19 11:00:07 -07:00
commit c5c473e29c
2 changed files with 42 additions and 46 deletions
Download patch file Download diff file Expand all files Collapse all files

63
drivers/cpufreq/powernow-k8.c
View file

@ -35,7 +35,6 @@
#include <linux/slab.h>
#include <linux/string.h>
#include <linux/cpumask.h>
#include <linux/sched.h> /* for current / set_cpus_allowed() */
#include <linux/io.h>
#include <linux/delay.h>
@ -1139,16 +1138,23 @@ static int transition_frequency_pstate(struct powernow_k8_data *data,
return res;
}
/* Driver entry point to switch to the target frequency */
static int powernowk8_target(struct cpufreq_policy *pol,
unsigned targfreq, unsigned relation)
struct powernowk8_target_arg {
struct cpufreq_policy *pol;
unsigned targfreq;
unsigned relation;
};
static long powernowk8_target_fn(void *arg)
{
cpumask_var_t oldmask;
struct powernowk8_target_arg *pta = arg;
struct cpufreq_policy *pol = pta->pol;
unsigned targfreq = pta->targfreq;
unsigned relation = pta->relation;
struct powernow_k8_data *data = per_cpu(powernow_data, pol->cpu);
u32 checkfid;
u32 checkvid;
unsigned int newstate;
int ret = -EIO;
int ret;
if (!data)
return -EINVAL;
@ -1156,29 +1162,16 @@ static int powernowk8_target(struct cpufreq_policy *pol,
checkfid = data->currfid;
checkvid = data->currvid;
/* only run on specific CPU from here on. */
/* This is poor form: use a workqueue or smp_call_function_single */
if (!alloc_cpumask_var(&oldmask, GFP_KERNEL))
return -ENOMEM;
cpumask_copy(oldmask, tsk_cpus_allowed(current));
set_cpus_allowed_ptr(current, cpumask_of(pol->cpu));
if (smp_processor_id() != pol->cpu) {
printk(KERN_ERR PFX "limiting to cpu %u failed\n", pol->cpu);
goto err_out;
}
if (pending_bit_stuck()) {
printk(KERN_ERR PFX "failing targ, change pending bit set\n");
goto err_out;
return -EIO;
}
pr_debug("targ: cpu %d, %d kHz, min %d, max %d, relation %d\n",
pol->cpu, targfreq, pol->min, pol->max, relation);
if (query_current_values_with_pending_wait(data))
goto err_out;
return -EIO;
if (cpu_family != CPU_HW_PSTATE) {
pr_debug("targ: curr fid 0x%x, vid 0x%x\n",
@ -1196,7 +1189,7 @@ static int powernowk8_target(struct cpufreq_policy *pol,
if (cpufreq_frequency_table_target(pol, data->powernow_table,
targfreq, relation, &newstate))
goto err_out;
return -EIO;
mutex_lock(&fidvid_mutex);
@ -1209,9 +1202,8 @@ static int powernowk8_target(struct cpufreq_policy *pol,
ret = transition_frequency_fidvid(data, newstate);
if (ret) {
printk(KERN_ERR PFX "transition frequency failed\n");
ret = 1;
mutex_unlock(&fidvid_mutex);
goto err_out;
return 1;
}
mutex_unlock(&fidvid_mutex);
@ -1220,12 +1212,25 @@ static int powernowk8_target(struct cpufreq_policy *pol,
data->powernow_table[newstate].index);
else
pol->cur = find_khz_freq_from_fid(data->currfid);
ret = 0;
err_out:
set_cpus_allowed_ptr(current, oldmask);
free_cpumask_var(oldmask);
return ret;
return 0;
}
/* Driver entry point to switch to the target frequency */
static int powernowk8_target(struct cpufreq_policy *pol,
unsigned targfreq, unsigned relation)
{
struct powernowk8_target_arg pta = { .pol = pol, .targfreq = targfreq,
.relation = relation };
/*
* Must run on @pol->cpu. cpufreq core is responsible for ensuring
* that we're bound to the current CPU and pol->cpu stays online.
*/
if (smp_processor_id() == pol->cpu)
return powernowk8_target_fn(&pta);
else
return work_on_cpu(pol->cpu, powernowk8_target_fn, &pta);
}
/* Driver entry point to verify the policy and range of frequencies */