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authorSteven Rostedt <rostedt@goodmis.org>2013-04-29 16:18:18 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2013-04-29 18:28:20 -0700
commitf91eb62f71b31e69e405663ff8d047bc3b9f7525 (patch)
tree7a61eb166aa50db4436dcaa3f5d0f385530dcb59 /init
parent8543ae1296f6ec1490c7afab6ae0fe97bf87ebf8 (diff)
downloadlinux-linaro-stable-f91eb62f71b31e69e405663ff8d047bc3b9f7525.tar.gz
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>
Diffstat (limited to 'init')
-rw-r--r--init/main.c13
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;
}