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author | Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> | 2011-10-04 19:44:38 +0900 |
---|---|---|
committer | Steven Rostedt <rostedt@goodmis.org> | 2011-10-10 15:13:03 -0400 |
commit | 02ca1521ad404cf566e0075848f80d064c0a0503 (patch) | |
tree | 11989ae5bfc1e32f355cc0bb0a64cb7ae801ed78 /kernel/trace | |
parent | 9d3ec7a0c41d010153c9d20577cb1bcf9c4f65df (diff) | |
download | op-kernel-dev-02ca1521ad404cf566e0075848f80d064c0a0503.zip op-kernel-dev-02ca1521ad404cf566e0075848f80d064c0a0503.tar.gz |
ftrace/kprobes: Fix not to delete probes if in use
Fix kprobe-tracer not to delete a probe if the probe is in use.
In that case, delete operation will return -EBUSY.
This bug can cause a kernel panic if enabled probes are deleted
during perf record.
(Add some probes on functions)
sh-4.2# perf probe --del probe:\*
sh-4.2# exit
(kernel panic)
This is originally reported on the fedora bugzilla:
https://bugzilla.redhat.com/show_bug.cgi?id=742383
I've also checked that this problem doesn't happen on
tracepoints when module removing because perf event
locks target module.
$ sudo ./perf record -e xfs:\* -aR sh
sh-4.2# rmmod xfs
ERROR: Module xfs is in use
sh-4.2# exit
[ perf record: Woken up 1 times to write data ]
[ perf record: Captured and wrote 0.203 MB perf.data (~8862 samples) ]
Signed-off-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Frank Ch. Eigler <fche@redhat.com>
Cc: stable@kernel.org
Link: http://lkml.kernel.org/r/20111004104438.14591.6553.stgit@fedora15
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Diffstat (limited to 'kernel/trace')
-rw-r--r-- | kernel/trace/trace_kprobe.c | 58 |
1 files changed, 49 insertions, 9 deletions
diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c index 5fb3697..00d527c 100644 --- a/kernel/trace/trace_kprobe.c +++ b/kernel/trace/trace_kprobe.c @@ -836,11 +836,17 @@ static void __unregister_trace_probe(struct trace_probe *tp) } /* Unregister a trace_probe and probe_event: call with locking probe_lock */ -static void unregister_trace_probe(struct trace_probe *tp) +static int unregister_trace_probe(struct trace_probe *tp) { + /* Enabled event can not be unregistered */ + if (trace_probe_is_enabled(tp)) + return -EBUSY; + __unregister_trace_probe(tp); list_del(&tp->list); unregister_probe_event(tp); + + return 0; } /* Register a trace_probe and probe_event */ @@ -854,7 +860,9 @@ static int register_trace_probe(struct trace_probe *tp) /* Delete old (same name) event if exist */ old_tp = find_trace_probe(tp->call.name, tp->call.class->system); if (old_tp) { - unregister_trace_probe(old_tp); + ret = unregister_trace_probe(old_tp); + if (ret < 0) + goto end; free_trace_probe(old_tp); } @@ -892,6 +900,7 @@ static int trace_probe_module_callback(struct notifier_block *nb, mutex_lock(&probe_lock); list_for_each_entry(tp, &probe_list, list) { if (trace_probe_within_module(tp, mod)) { + /* Don't need to check busy - this should have gone. */ __unregister_trace_probe(tp); ret = __register_trace_probe(tp); if (ret) @@ -1205,10 +1214,11 @@ static int create_trace_probe(int argc, char **argv) return -ENOENT; } /* delete an event */ - unregister_trace_probe(tp); - free_trace_probe(tp); + ret = unregister_trace_probe(tp); + if (ret == 0) + free_trace_probe(tp); mutex_unlock(&probe_lock); - return 0; + return ret; } if (argc < 2) { @@ -1317,18 +1327,29 @@ error: return ret; } -static void release_all_trace_probes(void) +static int release_all_trace_probes(void) { struct trace_probe *tp; + int ret = 0; mutex_lock(&probe_lock); + /* Ensure no probe is in use. */ + list_for_each_entry(tp, &probe_list, list) + if (trace_probe_is_enabled(tp)) { + ret = -EBUSY; + goto end; + } /* TODO: Use batch unregistration */ while (!list_empty(&probe_list)) { tp = list_entry(probe_list.next, struct trace_probe, list); unregister_trace_probe(tp); free_trace_probe(tp); } + +end: mutex_unlock(&probe_lock); + + return ret; } /* Probes listing interfaces */ @@ -1380,9 +1401,13 @@ static const struct seq_operations probes_seq_op = { static int probes_open(struct inode *inode, struct file *file) { - if ((file->f_mode & FMODE_WRITE) && - (file->f_flags & O_TRUNC)) - release_all_trace_probes(); + int ret; + + if ((file->f_mode & FMODE_WRITE) && (file->f_flags & O_TRUNC)) { + ret = release_all_trace_probes(); + if (ret < 0) + return ret; + } return seq_open(file, &probes_seq_op); } @@ -2055,6 +2080,21 @@ static __init int kprobe_trace_self_tests_init(void) ret = target(1, 2, 3, 4, 5, 6); + /* Disable trace points before removing it */ + tp = find_trace_probe("testprobe", KPROBE_EVENT_SYSTEM); + if (WARN_ON_ONCE(tp == NULL)) { + pr_warning("error on getting test probe.\n"); + warn++; + } else + disable_trace_probe(tp, TP_FLAG_TRACE); + + tp = find_trace_probe("testprobe2", KPROBE_EVENT_SYSTEM); + if (WARN_ON_ONCE(tp == NULL)) { + pr_warning("error on getting 2nd test probe.\n"); + warn++; + } else + disable_trace_probe(tp, TP_FLAG_TRACE); + ret = command_trace_probe("-:testprobe"); if (WARN_ON_ONCE(ret)) { pr_warning("error on deleting a probe.\n"); |