Messages in this thread Patch in this message | | | Date | Tue, 2 Jan 2007 13:27:58 -0800 | From | Venkatesh Pallipadi <> | Subject | Re: [PATCH] cpufreq lock rewrite bugfix - Fix locking in cpufreq_get |
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Incremental bugfix to previous 3 patch patchset of cpufreq lock rewrite.
There was one code path in cpufreq_get, that was using the write lock in place of read and also potential recursive lock with sysfs interface of cpuinfo_cur_freq.
Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Index: linux-2.6.20-rc-mm/drivers/cpufreq/cpufreq.c =================================================================== --- linux-2.6.20-rc-mm.orig/drivers/cpufreq/cpufreq.c +++ linux-2.6.20-rc-mm/drivers/cpufreq/cpufreq.c @@ -101,6 +101,7 @@ EXPORT_SYMBOL_GPL(unlock_policy_rwsem_wr /* internal prototypes */ static int __cpufreq_governor(struct cpufreq_policy *policy, unsigned int event); +static unsigned int __cpufreq_get(unsigned int cpu); static void handle_update(struct work_struct *work); /** @@ -488,7 +489,7 @@ store_one(scaling_max_freq,max); static ssize_t show_cpuinfo_cur_freq (struct cpufreq_policy * policy, char *buf) { - unsigned int cur_freq = cpufreq_get(policy->cpu); + unsigned int cur_freq = __cpufreq_get(policy->cpu); if (!cur_freq) return sprintf(buf, "<unknown>"); return sprintf(buf, "%u\n", cur_freq); @@ -1074,25 +1075,13 @@ unsigned int cpufreq_quick_get(unsigned EXPORT_SYMBOL(cpufreq_quick_get); -/** - * cpufreq_get - get the current CPU frequency (in kHz) - * @cpu: CPU number - * - * Get the CPU current (static) CPU frequency - */ -unsigned int cpufreq_get(unsigned int cpu) +static unsigned int __cpufreq_get(unsigned int cpu) { - struct cpufreq_policy *policy = cpufreq_cpu_get(cpu); + struct cpufreq_policy *policy = cpufreq_cpu_data[cpu]; unsigned int ret_freq = 0; - if (!policy) - return 0; - if (!cpufreq_driver->get) - goto out; - - if (unlikely(lock_policy_rwsem_write(cpu))) - goto out; + return (ret_freq); ret_freq = cpufreq_driver->get(cpu); @@ -1106,11 +1095,32 @@ unsigned int cpufreq_get(unsigned int cp } } - unlock_policy_rwsem_write(cpu); + return (ret_freq); +} + +/** + * cpufreq_get - get the current CPU frequency (in kHz) + * @cpu: CPU number + * + * Get the CPU current (static) CPU frequency + */ +unsigned int cpufreq_get(unsigned int cpu) +{ + unsigned int ret_freq = 0; + struct cpufreq_policy *policy = cpufreq_cpu_get(cpu); + + if (!policy) + goto out; + + if (unlikely(lock_policy_rwsem_read(cpu))) + goto out; + + ret_freq = __cpufreq_get(cpu); + + unlock_policy_rwsem_read(cpu); out: cpufreq_cpu_put(policy); - return (ret_freq); } EXPORT_SYMBOL(cpufreq_get); - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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