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author | Steven Rostedt <rostedt@goodmis.org> | 2013-04-30 03:18:18 +0400 |
---|---|---|
committer | Linus Torvalds <torvalds@linux-foundation.org> | 2013-04-30 05:28:20 +0400 |
commit | f91eb62f71b31e69e405663ff8d047bc3b9f7525 (patch) | |
tree | 7a61eb166aa50db4436dcaa3f5d0f385530dcb59 | |
parent | 8543ae1296f6ec1490c7afab6ae0fe97bf87ebf8 (diff) | |
download | linux-f91eb62f71b31e69e405663ff8d047bc3b9f7525.tar.xz |
init: scream bloody murder if interrupts are enabled too early
As I was testing a lot of my code recently, and having several
"successes", I accidentally noticed in the dmesg this little line:
start_kernel(): bug: interrupts were enabled *very* early, fixing it
Sure enough, one of my patches two commits ago enabled interrupts early.
The sad part here is that I never noticed it, and I ran several tests with
ktest too, and ktest did not notice this line.
What ktest looks for (and so does many other automated testing scripts) is
a back trace produced by a WARN_ON() or BUG(). As a back trace was never
produced, my buggy patch could have slipped into linux-next, or even
worse, mainline.
Adding a WARN(!irqs_disabled()) makes this bug a little more obvious:
PID hash table entries: 4096 (order: 3, 32768 bytes)
__ex_table already sorted, skipping sort
Checking aperture...
No AGP bridge found
Calgary: detecting Calgary via BIOS EBDA area
Calgary: Unable to locate Rio Grande table in EBDA - bailing!
Memory: 2003252k/2054848k available (4857k kernel code, 460k absent, 51136k reserved, 6210k data, 1096k init)
------------[ cut here ]------------
WARNING: at /home/rostedt/work/git/linux-trace.git/init/main.c:543 start_kernel+0x21e/0x415()
Hardware name: To Be Filled By O.E.M.
Interrupts were enabled *very* early, fixing it
Modules linked in:
Pid: 0, comm: swapper/0 Not tainted 3.8.0-test+ #286
Call Trace:
warn_slowpath_common+0x83/0x9b
warn_slowpath_fmt+0x46/0x48
start_kernel+0x21e/0x415
x86_64_start_reservations+0x10e/0x112
x86_64_start_kernel+0x102/0x111
---[ end trace 007d8b0491b4f5d8 ]---
Preemptible hierarchical RCU implementation.
RCU restricting CPUs from NR_CPUS=8 to nr_cpu_ids=4.
NR_IRQS:4352 nr_irqs:712 16
Console: colour VGA+ 80x25
console [ttyS0] enabled, bootconsole disabled
Do you see it?
The original version of this patch just slapped a WARN_ON() in there and
kept the printk(). Ard van Breemen suggested using the WARN() interface,
which makes the code a bit cleaner.
Also, while examining other warnings in init/main.c, I found two other
locations that deserve a bloody murder scream if their conditions are hit,
and updated them accordingly.
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Cc: Ard van Breemen <ard@telegraafnet.nl>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r-- | init/main.c | 13 |
1 files changed, 3 insertions, 10 deletions
diff --git a/init/main.c b/init/main.c index 63534a141b4e..26cd398acf2a 100644 --- a/init/main.c +++ b/init/main.c @@ -539,11 +539,8 @@ asmlinkage void __init start_kernel(void) * fragile until we cpu_idle() for the first time. */ preempt_disable(); - if (!irqs_disabled()) { - printk(KERN_WARNING "start_kernel(): bug: interrupts were " - "enabled *very* early, fixing it\n"); + if (WARN(!irqs_disabled(), "Interrupts were enabled *very* early, fixing it\n")) local_irq_disable(); - } idr_init_cache(); perf_event_init(); rcu_init(); @@ -558,9 +555,7 @@ asmlinkage void __init start_kernel(void) time_init(); profile_init(); call_function_init(); - if (!irqs_disabled()) - printk(KERN_CRIT "start_kernel(): bug: interrupts were " - "enabled early\n"); + WARN(!irqs_disabled(), "Interrupts were enabled early\n"); early_boot_irqs_disabled = false; local_irq_enable(); @@ -702,9 +697,7 @@ int __init_or_module do_one_initcall(initcall_t fn) strlcat(msgbuf, "disabled interrupts ", sizeof(msgbuf)); local_irq_enable(); } - if (msgbuf[0]) { - printk("initcall %pF returned with %s\n", fn, msgbuf); - } + WARN(msgbuf[0], "initcall %pF returned with %s\n", fn, msgbuf); return ret; } |