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author | Vivek Goyal <vgoyal@redhat.com> | 2010-10-22 09:48:43 +0200 |
---|---|---|
committer | Jens Axboe <jaxboe@fusionio.com> | 2010-10-22 09:48:43 +0200 |
commit | b4627321e18582dcbdeb45d77df29d3177107c65 (patch) | |
tree | f494dae7f39f219d73aa9752dfd3844293d65f50 /block/cfq-iosched.c | |
parent | 11a691bea48887c27425cc40bf291e74c922df25 (diff) | |
download | kernel_samsung_espresso10-b4627321e18582dcbdeb45d77df29d3177107c65.zip kernel_samsung_espresso10-b4627321e18582dcbdeb45d77df29d3177107c65.tar.gz kernel_samsung_espresso10-b4627321e18582dcbdeb45d77df29d3177107c65.tar.bz2 |
cfq-iosched: Fix a gcc 4.5 warning and put some comments
- Andi encountedred following warning with gcc 4.5
linux/block/cfq-iosched.c: In function ‘cfq_dispatch_requests’:
linux/block/cfq-iosched.c:2156:3: warning: array subscript is above array
bounds
- Warning happens due to following code.
slice = group_slice * count /
max_t(unsigned, cfqg->busy_queues_avg[cfqd->serving_prio],
cfq_group_busy_queues_wl(cfqd->serving_prio, cfqd, cfqg));
gcc is complaining about cfqg->busy_queues_avg[] being indexed by CFQ
prio classes (RT, BE and IDLE) while the array size is only 2.
- At run time, we never access cfqg->busy_queues_avg[IDLE] and return from
function before this code hits.
- To fix warning increase the array size though it will remain unused. This
patch also puts some comments to clarify some of the confusions.
- I have taken Jens's patch and modified it a bit.
- Compile tested with gcc 4.4 and boot tested. I don't have gcc 4.5
running, Andi can you please test it with gcc 4.5 to make sure it
worked.
Reported-by: Andi Kleen <ak@linux.intel.com>
Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
Acked-by: Jeff Moyer <jmoyer@redhat.com>
Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
Diffstat (limited to 'block/cfq-iosched.c')
-rw-r--r-- | block/cfq-iosched.c | 16 |
1 files changed, 13 insertions, 3 deletions
diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c index 86338d5..dfceb63 100644 --- a/block/cfq-iosched.c +++ b/block/cfq-iosched.c @@ -157,6 +157,7 @@ enum wl_prio_t { BE_WORKLOAD = 0, RT_WORKLOAD = 1, IDLE_WORKLOAD = 2, + CFQ_PRIO_NR, }; /* @@ -181,10 +182,19 @@ struct cfq_group { /* number of cfqq currently on this group */ int nr_cfqq; - /* Per group busy queus average. Useful for workload slice calc. */ - unsigned int busy_queues_avg[2]; /* - * rr lists of queues with requests, onle rr for each priority class. + * Per group busy queus average. Useful for workload slice calc. We + * create the array for each prio class but at run time it is used + * only for RT and BE class and slot for IDLE class remains unused. + * This is primarily done to avoid confusion and a gcc warning. + */ + unsigned int busy_queues_avg[CFQ_PRIO_NR]; + /* + * rr lists of queues with requests. We maintain service trees for + * RT and BE classes. These trees are subdivided in subclasses + * of SYNC, SYNC_NOIDLE and ASYNC based on workload type. For IDLE + * class there is no subclassification and all the cfq queues go on + * a single tree service_tree_idle. * Counts are embedded in the cfq_rb_root */ struct cfq_rb_root service_trees[2][3]; |