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[PATCH] fix race in idr code 

I ran into a bug where the kernel died in the idr code:

cpu 0x1d: Vector: 300 (Data Access) at [c000000b7096f710]
    pc: c0000000001f8984: .idr_get_new_above_int+0x140/0x330
    lr: c0000000001f89b4: .idr_get_new_above_int+0x170/0x330
    sp: c000000b7096f990
   msr: 800000000000b032
   dar: 0
 dsisr: 40010000
  current = 0xc000000b70d43830
  paca    = 0xc000000000556900
    pid   = 2022, comm = hwup
1d:mon> t
[c000000b7096f990] c0000000000d2ad8 .expand_files+0x2e8/0x364 (unreliable)
[c000000b7096faa0] c0000000001f8bf8 .idr_get_new_above+0x18/0x68
[c000000b7096fb20] c00000000002a054 .init_new_context+0x5c/0xf0
[c000000b7096fbc0] c000000000049dc8 .copy_process+0x91c/0x1404
[c000000b7096fcd0] c00000000004a988 .do_fork+0xd8/0x224
[c000000b7096fdc0] c00000000000ebdc .sys_clone+0x5c/0x74
[c000000b7096fe30] c000000000008950 .ppc_clone+0x8/0xc
This commit is contained in:
Sonny Rao 2006-06-25 05:49:34 -07:00 committed by Linus Torvalds
parent a45219483e
commit 1eec00565d
1 changed files with 12 additions and 4 deletions
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16
lib/idr.c
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@ -48,15 +48,21 @@ static struct idr_layer *alloc_layer(struct idr *idp)
return(p);
}
/* only called when idp->lock is held */
static void __free_layer(struct idr *idp, struct idr_layer *p)
{
p->ary[0] = idp->id_free;
idp->id_free = p;
idp->id_free_cnt++;
}
static void free_layer(struct idr *idp, struct idr_layer *p)
{
/*
* Depends on the return element being zeroed.
*/
spin_lock(&idp->lock);
p->ary[0] = idp->id_free;
idp->id_free = p;
idp->id_free_cnt++;
__free_layer(idp, p);
spin_unlock(&idp->lock);
}
@ -184,12 +190,14 @@ build_up:
* The allocation failed. If we built part of
* the structure tear it down.
*/
spin_lock(&idp->lock);
for (new = p; p && p != idp->top; new = p) {
p = p->ary[0];
new->ary[0] = NULL;
new->bitmap = new->count = 0;
free_layer(idp, new);
__free_layer(idp, new);
}
spin_unlock(&idp->lock);
return -1;
}
new->ary[0] = p;