The patch titled
Subject: kernel/printk/printk.c: revert "printk: enable interrupts before calling console_trylock_for_printk()"
has been added to the -mm tree. Its filename is
kernel-printk-printkc-revert-printk-enable-interrupts-before-calling-console_trylock_for_printk.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/kernel-printk-printkc-revert-printk-enable-interrupts-before-calling-console_trylock_for_printk.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/kernel-printk-printkc-revert-printk-enable-interrupts-before-calling-console_trylock_for_printk.patch
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------------------------------------------------------
From: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Subject: kernel/printk/printk.c: revert "printk: enable interrupts before calling console_trylock_for_printk()"
Revert 939f04bec1a4 ("printk: enable interrupts before calling
console_trylock_for_printk()").
Andreas reported:
: None of the post 3.15 kernel boot for me. They all hang at the GRUB
: screen telling me it loaded and started the kernel, but the kernel
: itself stops before it prints anything (or even replaces the GRUB
: background graphics).
939f04bec1a4 is modest latency reduction. Revert it until we understand
the reason for these failures.
Reported-by: Andreas Bombe <aeb@xxxxxxxxxx>
Cc: Jan Kara <jack@xxxxxxx>
Cc: Steven Rostedt <rostedt@xxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
kernel/printk/printk.c | 44 +++++++++++++++------------------------
1 file changed, 18 insertions(+), 26 deletions(-)
diff -puN kernel/printk/printk.c~kernel-printk-printkc-revert-printk-enable-interrupts-before-calling-console_trylock_for_printk kernel/printk/printk.c
--- a/kernel/printk/printk.c~kernel-printk-printkc-revert-printk-enable-interrupts-before-calling-console_trylock_for_printk
+++ a/kernel/printk/printk.c
@@ -1416,9 +1416,10 @@ static int have_callable_console(void)
/*
* Can we actually use the console at this time on this cpu?
*
- * Console drivers may assume that per-cpu resources have been allocated. So
- * unless they're explicitly marked as being able to cope (CON_ANYTIME) don't
- * call them until this CPU is officially up.
+ * Console drivers may assume that per-cpu resources have
+ * been allocated. So unless they're explicitly marked as
+ * being able to cope (CON_ANYTIME) don't call them until
+ * this CPU is officially up.
*/
static inline int can_use_console(unsigned int cpu)
{
@@ -1431,10 +1432,8 @@ static inline int can_use_console(unsign
* console_lock held, and 'console_locked' set) if it
* is successful, false otherwise.
*/
-static int console_trylock_for_printk(void)
+static int console_trylock_for_printk(unsigned int cpu)
{
- unsigned int cpu = smp_processor_id();
-
if (!console_trylock())
return 0;
/*
@@ -1609,8 +1608,7 @@ asmlinkage int vprintk_emit(int facility
*/
if (!oops_in_progress && !lockdep_recursing(current)) {
recursion_bug = 1;
- local_irq_restore(flags);
- return 0;
+ goto out_restore_irqs;
}
zap_locks();
}
@@ -1718,27 +1716,21 @@ asmlinkage int vprintk_emit(int facility
logbuf_cpu = UINT_MAX;
raw_spin_unlock(&logbuf_lock);
- lockdep_on();
- local_irq_restore(flags);
/* If called from the scheduler, we can not call up(). */
- if (in_sched)
- return printed_len;
-
- /*
- * Disable preemption to avoid being preempted while holding
- * console_sem which would prevent anyone from printing to console
- */
- preempt_disable();
- /*
- * Try to acquire and then immediately release the console semaphore.
- * The release will print out buffers and wake up /dev/kmsg and syslog()
- * users.
- */
- if (console_trylock_for_printk())
- console_unlock();
- preempt_enable();
+ if (!in_sched) {
+ /*
+ * Try to acquire and then immediately release the console
+ * semaphore. The release will print out buffers and wake up
+ * /dev/kmsg and syslog() users.
+ */
+ if (console_trylock_for_printk(this_cpu))
+ console_unlock();
+ }
+ lockdep_on();
+out_restore_irqs:
+ local_irq_restore(flags);
return printed_len;
}
EXPORT_SYMBOL(vprintk_emit);
_
Patches currently in -mm which might be from akpm@xxxxxxxxxxxxxxxxxxxx are
i-need-old-gcc.patch
arch-alpha-kernel-systblss-remove-debug-check.patch
maintainers-akpm-maintenance.patch
kernel-printk-printkc-revert-printk-enable-interrupts-before-calling-console_trylock_for_printk.patch
x86-numa-setup_node_data-drop-dead-code-and-rename-function-checkpatch-fixes.patch
kernel-posix-timersc-code-clean-up-checkpatch-fixes.patch
input-route-kbd-leds-through-the-generic-leds-layer.patch
ocfs2-free-inode-when-i_count-becomes-zero-checkpatch-fixes.patch
mm.patch
slub-use-new-node-functions-checkpatch-fixes.patch
slab-use-get_node-and-kmem_cache_node-functions-fix-2.patch
slab-use-get_node-and-kmem_cache_node-functions-fix-2-fix.patch
mm-page_allocc-unexport-alloc_pages_exact_nid.patch
dma-cma-support-arbitrary-bitmap-granularity-fix.patch
mm-hugetlbfs-fix-rmapping-for-anonymous-hugepages-with-page_pgoff-v3-fix.patch
mm-vmallocc-add-a-schedule-point-to-vmalloc-fix.patch
include-linux-mmdebugh-add-vm_warn_once.patch
mm-catch-memory-commitment-underflow-fix.patch
mm-introduce-do_shared_fault-and-drop-do_fault-fix-fix.patch
mm-compactionc-isolate_freepages_block-small-tuneup.patch
mm-zpool-implement-common-zpool-api-to-zbud-zsmalloc-fix.patch
mm-zpool-prevent-zbud-zsmalloc-from-unloading-when-used-checkpatch-fixes.patch
do_shared_fault-check-that-mmap_sem-is-held.patch
list-fix-order-of-arguments-for-hlist_add_after_rcu-checkpatch-fixes.patch
add-lib-globc-fix.patch
lib-list_sortc-convert-to-pr_foo.patch
lib-list_sortc-convert-to-pr_foo-fix.patch
binfmt_elfc-use-get_random_int-to-fix-entropy-depleting-fix.patch
fs-isofs-logging-clean-up-fix.patch
kexec-implementation-of-new-syscall-kexec_file_load-checkpatch-fixes.patch
panic-add-taint_softlockup-fix.patch
linux-next.patch
drivers-gpio-gpio-zevioc-fix-build.patch
drivers-staging-emxx_udc-emxx_udcc-replace-strict_strto-with-kstrto.patch
mm-replace-remap_file_pages-syscall-with-emulation-fix.patch
memcg-deprecate-memoryforce_empty-knob-fix.patch
debugging-keep-track-of-page-owners.patch
journal_add_journal_head-debug.patch
journal_add_journal_head-debug-fix.patch
kernel-forkc-export-kernel_thread-to-modules.patch
mutex-subsystem-synchro-test-module.patch
slab-leaks3-default-y.patch
put_bh-debug.patch
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