diff options
author | Ingo Molnar <mingo@elte.hu> | 2009-05-19 03:22:19 -0400 |
---|---|---|
committer | Ingo Molnar <mingo@elte.hu> | 2009-05-19 03:22:19 -0400 |
commit | 4200efd9acda4accf24640f1e77d24fdcdb524df (patch) | |
tree | ffeda24ae6a9c1b8ca94615e261434d925d2ed2c | |
parent | 2d02494f5a90f2e4b3c4c6acc85ec94674cdc431 (diff) |
sched: properly define the sched_group::cpumask and sched_domain::span fields
Properly document the variable-size structure tricks we are doing
wrt. struct sched_group and sched_domain, and use the field[0] GCC
extension instead of defining a vla array.
Dont use unions for this, as pointed out by Linus.
[ Impact: cleanup, un-confuse Sparse and LLVM ]
Reported-by: Jeff Garzik <jeff@garzik.org>
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
LKML-Reference: <alpine.LFD.2.01.0905180850110.3301@localhost.localdomain>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
-rw-r--r-- | include/linux/sched.h | 25 | ||||
-rw-r--r-- | kernel/sched.c | 5 |
2 files changed, 25 insertions, 5 deletions
diff --git a/include/linux/sched.h b/include/linux/sched.h index de7b3b217772..dbb1043e8656 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h | |||
@@ -839,7 +839,17 @@ struct sched_group { | |||
839 | */ | 839 | */ |
840 | u32 reciprocal_cpu_power; | 840 | u32 reciprocal_cpu_power; |
841 | 841 | ||
842 | unsigned long cpumask[]; | 842 | /* |
843 | * The CPUs this group covers. | ||
844 | * | ||
845 | * NOTE: this field is variable length. (Allocated dynamically | ||
846 | * by attaching extra space to the end of the structure, | ||
847 | * depending on how many CPUs the kernel has booted up with) | ||
848 | * | ||
849 | * It is also be embedded into static data structures at build | ||
850 | * time. (See 'struct static_sched_group' in kernel/sched.c) | ||
851 | */ | ||
852 | unsigned long cpumask[0]; | ||
843 | }; | 853 | }; |
844 | 854 | ||
845 | static inline struct cpumask *sched_group_cpus(struct sched_group *sg) | 855 | static inline struct cpumask *sched_group_cpus(struct sched_group *sg) |
@@ -925,8 +935,17 @@ struct sched_domain { | |||
925 | char *name; | 935 | char *name; |
926 | #endif | 936 | #endif |
927 | 937 | ||
928 | /* span of all CPUs in this domain */ | 938 | /* |
929 | unsigned long span[]; | 939 | * Span of all CPUs in this domain. |
940 | * | ||
941 | * NOTE: this field is variable length. (Allocated dynamically | ||
942 | * by attaching extra space to the end of the structure, | ||
943 | * depending on how many CPUs the kernel has booted up with) | ||
944 | * | ||
945 | * It is also be embedded into static data structures at build | ||
946 | * time. (See 'struct static_sched_domain' in kernel/sched.c) | ||
947 | */ | ||
948 | unsigned long span[0]; | ||
930 | }; | 949 | }; |
931 | 950 | ||
932 | static inline struct cpumask *sched_domain_span(struct sched_domain *sd) | 951 | static inline struct cpumask *sched_domain_span(struct sched_domain *sd) |
diff --git a/kernel/sched.c b/kernel/sched.c index 497c09ba61e7..228acae8821f 100644 --- a/kernel/sched.c +++ b/kernel/sched.c | |||
@@ -7948,8 +7948,9 @@ int sched_smt_power_savings = 0, sched_mc_power_savings = 0; | |||
7948 | 7948 | ||
7949 | /* | 7949 | /* |
7950 | * The cpus mask in sched_group and sched_domain hangs off the end. | 7950 | * The cpus mask in sched_group and sched_domain hangs off the end. |
7951 | * FIXME: use cpumask_var_t or dynamic percpu alloc to avoid wasting space | 7951 | * |
7952 | * for nr_cpu_ids < CONFIG_NR_CPUS. | 7952 | * ( See the the comments in include/linux/sched.h:struct sched_group |
7953 | * and struct sched_domain. ) | ||
7953 | */ | 7954 | */ |
7954 | struct static_sched_group { | 7955 | struct static_sched_group { |
7955 | struct sched_group sg; | 7956 | struct sched_group sg; |