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authorIngo Molnar <mingo@elte.hu>2008-11-19 10:00:15 +0100
committerIngo Molnar <mingo@elte.hu>2008-11-19 10:00:15 +0100
commit86fa2f60674540df0b34f5c547ed0c1cf3a8f212 (patch)
treea367d69ad41f46362dfdb8eaf19ec8a6f8a8c812 /kernel/trace/trace.c
parenta22506347d038a66506c6f57e9b97104128e280d (diff)
downloadop-kernel-dev-86fa2f60674540df0b34f5c547ed0c1cf3a8f212.zip
op-kernel-dev-86fa2f60674540df0b34f5c547ed0c1cf3a8f212.tar.gz
ftrace: fix selftest locking
Impact: fix self-test boot crash Self-test failure forgot to re-lock the BKL - crashing the next initcall: Testing tracer irqsoff: .. no entries found ..FAILED! initcall init_irqsoff_tracer+0x0/0x11 returned 0 after 3906 usecs calling init_mmio_trace+0x0/0xf @ 1 ------------[ cut here ]------------ Kernel BUG at c0c0a915 [verbose debug info unavailable] invalid opcode: 0000 [#1] SMP DEBUG_PAGEALLOC last sysfs file: Pid: 1, comm: swapper Not tainted (2.6.28-rc5-tip #53704) EIP: 0060:[<c0c0a915>] EFLAGS: 00010286 CPU: 1 EIP is at unlock_kernel+0x10/0x2b EAX: ffffffff EBX: 00000000 ECX: 00000000 EDX: f7030000 ESI: c12da19c EDI: 00000000 EBP: f7039f54 ESP: f7039f54 DS: 007b ES: 007b FS: 00d8 GS: 0000 SS: 0068 Process swapper (pid: 1, ti=f7038000 task=f7030000 task.ti=f7038000) Stack: f7039f6c c0164d30 c013fed8 a7d8d7b4 00000000 00000000 f7039f74 c12fb78a f7039fd0 c0101132 c12fb77d 00000000 6f727200 6f632072 2d206564 c1002031 0000000f f7039fa2 f7039fb0 3531b171 00000000 00000000 0000002f c12ca480 Call Trace: [<c0164d30>] ? register_tracer+0x66/0x13f [<c013fed8>] ? ktime_get+0x19/0x1b [<c12fb78a>] ? init_mmio_trace+0xd/0xf [<c0101132>] ? do_one_initcall+0x4a/0x111 [<c12fb77d>] ? init_mmio_trace+0x0/0xf [<c015c7e6>] ? init_irq_proc+0x46/0x59 [<c12e851d>] ? kernel_init+0x104/0x152 [<c12e8419>] ? kernel_init+0x0/0x152 [<c01038b7>] ? kernel_thread_helper+0x7/0x10 Code: 58 14 43 75 0a b8 00 9b 2d c1 e8 51 43 7a ff 64 a1 00 a0 37 c1 89 58 14 5b 5d c3 55 64 8b 15 00 a0 37 c1 83 7a 14 00 89 e5 79 04 <0f> 0b eb fe 8b 42 14 48 85 c0 89 42 14 79 0a b8 00 9b 2d c1 e8 EIP: [<c0c0a915>] unlock_kernel+0x10/0x2b SS:ESP 0068:f7039f54 ---[ end trace a7919e7f17c0a725 ]--- Kernel panic - not syncing: Attempted to kill init! So clean up the flow a bit. Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'kernel/trace/trace.c')
-rw-r--r--kernel/trace/trace.c25
1 files changed, 13 insertions, 12 deletions
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 1689212..24b6238 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -520,7 +520,15 @@ int register_tracer(struct tracer *type)
return -1;
}
+ /*
+ * When this gets called we hold the BKL which means that
+ * preemption is disabled. Various trace selftests however
+ * need to disable and enable preemption for successful tests.
+ * So we drop the BKL here and grab it after the tests again.
+ */
+ unlock_kernel();
mutex_lock(&trace_types_lock);
+
for (t = trace_types; t; t = t->next) {
if (strcmp(type->name, t->name) == 0) {
/* already found */
@@ -532,13 +540,6 @@ int register_tracer(struct tracer *type)
}
#ifdef CONFIG_FTRACE_STARTUP_TEST
- /*
- * When this gets called we hold the BKL which means that preemption
- * is disabled. Various trace selftests however need to disable
- * and enable preemption for successful tests. So we drop the BKL here
- * and grab it after the tests again.
- */
- unlock_kernel();
if (type->selftest) {
struct tracer *saved_tracer = current_trace;
struct trace_array *tr = &global_trace;
@@ -550,9 +551,9 @@ int register_tracer(struct tracer *type)
* internal tracing to verify that everything is in order.
* If we fail, we do not register this tracer.
*/
- for_each_tracing_cpu(i) {
+ for_each_tracing_cpu(i)
tracing_reset(tr, i);
- }
+
current_trace = type;
/* the test is responsible for initializing and enabling */
pr_info("Testing tracer %s: ", type->name);
@@ -564,12 +565,11 @@ int register_tracer(struct tracer *type)
goto out;
}
/* Only reset on passing, to avoid touching corrupted buffers */
- for_each_tracing_cpu(i) {
+ for_each_tracing_cpu(i)
tracing_reset(tr, i);
- }
+
printk(KERN_CONT "PASSED\n");
}
- lock_kernel();
#endif
type->next = trace_types;
@@ -580,6 +580,7 @@ int register_tracer(struct tracer *type)
out:
mutex_unlock(&trace_types_lock);
+ lock_kernel();
return ret;
}
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