From: KOSAKI Motohiro Date: Tue, 26 Jul 2011 23:08:45 +0000 (-0700) Subject: cpumask: add cpumask_var_t documentation X-Git-Tag: v3.1-rc1~186 X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=a64a26e822ddb739de464540dfd2cbb6abce47d5;p=profile%2Fivi%2Fkernel-adaptation-intel-automotive.git cpumask: add cpumask_var_t documentation cpumask_var_t has one notable difference from cpumask_t. Add the explanation. Signed-off-by: KOSAKI Motohiro Cc: Thiago Farina Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- diff --git a/include/linux/cpumask.h b/include/linux/cpumask.h index b24ac56..4f7a632 100644 --- a/include/linux/cpumask.h +++ b/include/linux/cpumask.h @@ -617,6 +617,20 @@ static inline size_t cpumask_size(void) * ... use 'tmpmask' like a normal struct cpumask * ... * * free_cpumask_var(tmpmask); + * + * + * However, one notable exception is there. alloc_cpumask_var() allocates + * only nr_cpumask_bits bits (in the other hand, real cpumask_t always has + * NR_CPUS bits). Therefore you don't have to dereference cpumask_var_t. + * + * cpumask_var_t tmpmask; + * if (!alloc_cpumask_var(&tmpmask, GFP_KERNEL)) + * return -ENOMEM; + * + * var = *tmpmask; + * + * This code makes NR_CPUS length memcopy and brings to a memory corruption. + * cpumask_copy() provide safe copy functionality. */ #ifdef CONFIG_CPUMASK_OFFSTACK typedef struct cpumask *cpumask_var_t;