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| author | Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> | 2010-12-03 18:54:16 +0900 |
|---|---|---|
| committer | Ingo Molnar <mingo@elte.hu> | 2010-12-06 17:59:31 +0100 |
| commit | 0490cd1f9d99569d3bd64e17adc88db06a5007be (patch) | |
| tree | a857099ce331773d5103f376860dd3f29f7a8b54 /kernel | |
| parent | 6274de4984a630b45c6934b3ee62e5692c745328 (diff) | |
| download | lwn-0490cd1f9d99569d3bd64e17adc88db06a5007be.tar.gz lwn-0490cd1f9d99569d3bd64e17adc88db06a5007be.zip | |
kprobes: Reuse unused kprobe
Reuse unused (waiting for unoptimizing and no user handler)
kprobe on given address instead of returning -EBUSY for
registering a new kprobe.
Signed-off-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
Cc: Jason Baron <jbaron@redhat.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: 2nddept-manager@sdl.hitachi.co.jp
LKML-Reference: <20101203095416.2961.39080.stgit@ltc236.sdl.hitachi.co.jp>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/kprobes.c | 32 |
1 files changed, 30 insertions, 2 deletions
diff --git a/kernel/kprobes.c b/kernel/kprobes.c index ba4d4c0740cf..134754d18bb4 100644 --- a/kernel/kprobes.c +++ b/kernel/kprobes.c @@ -692,6 +692,27 @@ static __kprobes void unoptimize_kprobe(struct kprobe *p, bool force) } } +/* Cancel unoptimizing for reusing */ +static void reuse_unused_kprobe(struct kprobe *ap) +{ + struct optimized_kprobe *op; + + BUG_ON(!kprobe_unused(ap)); + /* + * Unused kprobe MUST be on the way of delayed unoptimizing (means + * there is still a relative jump) and disabled. + */ + op = container_of(ap, struct optimized_kprobe, kp); + if (unlikely(list_empty(&op->list))) + printk(KERN_WARNING "Warning: found a stray unused " + "aggrprobe@%p\n", ap->addr); + /* Enable the probe again */ + ap->flags &= ~KPROBE_FLAG_DISABLED; + /* Optimize it again (remove from op->list) */ + BUG_ON(!kprobe_optready(ap)); + optimize_kprobe(ap); +} + /* Remove optimized instructions */ static void __kprobes kill_optimized_kprobe(struct kprobe *p) { @@ -872,6 +893,13 @@ static void __kprobes __disarm_kprobe(struct kprobe *p, bool reopt) #define kprobe_disarmed(p) kprobe_disabled(p) #define wait_for_kprobe_optimizer() do {} while (0) +/* There should be no unused kprobes can be reused without optimization */ +static void reuse_unused_kprobe(struct kprobe *ap) +{ + printk(KERN_ERR "Error: There should be no unused kprobe here.\n"); + BUG_ON(kprobe_unused(ap)); +} + static __kprobes void free_aggr_kprobe(struct kprobe *p) { arch_remove_kprobe(p); @@ -1173,8 +1201,8 @@ static int __kprobes register_aggr_kprobe(struct kprobe *orig_p, return -ENOMEM; init_aggr_kprobe(ap, orig_p); } else if (kprobe_unused(ap)) - /* Busy to die */ - return -EBUSY; + /* This probe is going to die. Rescue it */ + reuse_unused_kprobe(ap); if (kprobe_gone(ap)) { /* |