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Commit ffea73fc723a12fdde4c9fb3fcce5d154d1104a1

Authored by Tejun Heo
Committed by Jens Axboe
1 parent fd7949564c
Exists in smarc-l5.0.0_1.0.0-ga and in 5 other branches imx_3.10.17_1.0.1_ga, imx_3.10.53_1.1.0_ga, imx_3.14.28_1.0.0_ga, smarc-imx_3.10.53_1.1.0_ga, smarc-imx_3.14.28_1.0.0_ga

block: blkcg_policy_cfq shouldn't be used if !CONFIG_CFQ_GROUP_IOSCHED 

cfq may be built w/ or w/o blkcg support depending on
CONFIG_CFQ_CGROUP_IOSCHED.  If blkcg support is disabled, most of
related code is ifdef'd out but some part is left dangling -
blkcg_policy_cfq is left zero-filled and blkcg_policy_[un]register()
calls are made on it.

Feeding zero filled policy to blkcg_policy_register() is incorrect and
triggers the following WARN_ON() if CONFIG_BLK_CGROUP &&
!CONFIG_CFQ_GROUP_IOSCHED.

 ------------[ cut here ]------------
 WARNING: at block/blk-cgroup.c:867
 Modules linked in:
 Modules linked in:
 CPU: 3 Not tainted 3.4.0-09547-gfb21aff #1
 Process swapper/0 (pid: 1, task: 000000003ff80000, ksp: 000000003ff7f8b8)
 Krnl PSW : 0704100180000000 00000000003d76ca (blkcg_policy_register+0xca/0xe0)
	    R:0 T:1 IO:1 EX:1 Key:0 M:1 W:0 P:0 AS:0 CC:1 PM:0 EA:3
 Krnl GPRS: 0000000000000000 00000000014b85ec 00000000014b85b0 0000000000000000
	    000000000096fb60 0000000000000000 00000000009a8e78 0000000000000048
	    000000000099c070 0000000000b6f000 0000000000000000 000000000099c0b8
	    00000000014b85b0 0000000000667580 000000003ff7fd98 000000003ff7fd70
 Krnl Code: 00000000003d76be: a7280001           lhi     %r2,1
	    00000000003d76c2: a7f4ffdf           brc     15,3d7680
	   #00000000003d76c6: a7f40001           brc     15,3d76c8
	   >00000000003d76ca: a7c8ffea           lhi     %r12,-22
	    00000000003d76ce: a7f4ffce           brc     15,3d766a
	    00000000003d76d2: a7f40001           brc     15,3d76d4
	    00000000003d76d6: a7c80000           lhi     %r12,0
	    00000000003d76da: a7f4ffc2           brc     15,3d765e
 Call Trace:
 ([<0000000000b6f000>] initcall_debug+0x0/0x4)
  [<0000000000989e8a>] cfq_init+0x62/0xd4
  [<00000000001000ba>] do_one_initcall+0x3a/0x170
  [<000000000096fb60>] kernel_init+0x214/0x2bc
  [<0000000000623202>] kernel_thread_starter+0x6/0xc
  [<00000000006231fc>] kernel_thread_starter+0x0/0xc
 no locks held by swapper/0/1.
 Last Breaking-Event-Address:
  [<00000000003d76c6>] blkcg_policy_register+0xc6/0xe0
 ---[ end trace b8ef4903fcbf9dd3 ]---

This patch fixes the problem by ensuring all blkcg support code is
inside CONFIG_CFQ_GROUP_IOSCHED.

* blkcg_policy_cfq declaration and blkg_to_cfqg() definition are moved
  inside the first CONFIG_CFQ_GROUP_IOSCHED block.  __maybe_unused is
  dropped from blkcg_policy_cfq decl.

* blkcg_deactivate_poilcy() invocation is moved inside ifdef.  This
  also makes the activation logic match cfq_init_queue().

* All blkcg_policy_[un]register() invocations are moved inside ifdef.

Signed-off-by: Tejun Heo <tj@kernel.org>
Reported-by: Heiko Carstens <heiko.carstens@de.ibm.com>
LKML-Reference: <20120601112954.GC3535@osiris.boeblingen.de.ibm.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

Showing 1 changed file with 17 additions and 12 deletions Side-by-side Diff

... ... @@ -17,8 +17,6 @@
17 17 #include "blk.h"
18 18 #include "blk-cgroup.h"
19 19  
20   -static struct blkcg_policy blkcg_policy_cfq __maybe_unused;
21   -
22 20 /*
23 21 * tunables
24 22 */
... ... @@ -418,11 +416,6 @@
418 416 return pd ? container_of(pd, struct cfq_group, pd) : NULL;
419 417 }
420 418  
421   -static inline struct cfq_group *blkg_to_cfqg(struct blkcg_gq *blkg)
422   -{
423   - return pd_to_cfqg(blkg_to_pd(blkg, &blkcg_policy_cfq));
424   -}
425   -
426 419 static inline struct blkcg_gq *cfqg_to_blkg(struct cfq_group *cfqg)
427 420 {
428 421 return pd_to_blkg(&cfqg->pd);
... ... @@ -572,6 +565,13 @@
572 565  
573 566 #ifdef CONFIG_CFQ_GROUP_IOSCHED
574 567  
  568 +static struct blkcg_policy blkcg_policy_cfq;
  569 +
  570 +static inline struct cfq_group *blkg_to_cfqg(struct blkcg_gq *blkg)
  571 +{
  572 + return pd_to_cfqg(blkg_to_pd(blkg, &blkcg_policy_cfq));
  573 +}
  574 +
575 575 static inline void cfqg_get(struct cfq_group *cfqg)
576 576 {
577 577 return blkg_get(cfqg_to_blkg(cfqg));
578 578  
... ... @@ -3951,10 +3951,11 @@
3951 3951  
3952 3952 cfq_shutdown_timer_wq(cfqd);
3953 3953  
3954   -#ifndef CONFIG_CFQ_GROUP_IOSCHED
  3954 +#ifdef CONFIG_CFQ_GROUP_IOSCHED
  3955 + blkcg_deactivate_policy(q, &blkcg_policy_cfq);
  3956 +#else
3955 3957 kfree(cfqd->root_group);
3956 3958 #endif
3957   - blkcg_deactivate_policy(q, &blkcg_policy_cfq);
3958 3959 kfree(cfqd);
3959 3960 }
3960 3961  
3961 3962  
... ... @@ -4194,13 +4195,13 @@
4194 4195 #ifdef CONFIG_CFQ_GROUP_IOSCHED
4195 4196 if (!cfq_group_idle)
4196 4197 cfq_group_idle = 1;
4197   -#else
4198   - cfq_group_idle = 0;
4199   -#endif
4200 4198  
4201 4199 ret = blkcg_policy_register(&blkcg_policy_cfq);
4202 4200 if (ret)
4203 4201 return ret;
  4202 +#else
  4203 + cfq_group_idle = 0;
  4204 +#endif
4204 4205  
4205 4206 ret = -ENOMEM;
4206 4207 cfq_pool = KMEM_CACHE(cfq_queue, 0);
4207 4208  
4208 4209  
4209 4210  
... ... @@ -4216,13 +4217,17 @@
4216 4217 err_free_pool:
4217 4218 kmem_cache_destroy(cfq_pool);
4218 4219 err_pol_unreg:
  4220 +#ifdef CONFIG_CFQ_GROUP_IOSCHED
4219 4221 blkcg_policy_unregister(&blkcg_policy_cfq);
  4222 +#endif
4220 4223 return ret;
4221 4224 }
4222 4225  
4223 4226 static void __exit cfq_exit(void)
4224 4227 {
  4228 +#ifdef CONFIG_CFQ_GROUP_IOSCHED
4225 4229 blkcg_policy_unregister(&blkcg_policy_cfq);
  4230 +#endif
4226 4231 elv_unregister(&iosched_cfq);
4227 4232 kmem_cache_destroy(cfq_pool);
4228 4233 }