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authorLinus Torvalds <torvalds@linux-foundation.org>2017-11-18 01:58:01 +0300
committerLinus Torvalds <torvalds@linux-foundation.org>2017-11-18 01:58:01 +0300
commit2dcd9c71c1ffa9a036e09047f60e08383bb0abb6 (patch)
tree8caabaf493288a3d5adb46ac49ad5097d0c907c7 /kernel/printk
parentb1c2a344cc19b40d2f1e7cbd9c2f4f205ae6d650 (diff)
parenta96a5037ed0f52e2d86739f4a1ef985bd036e575 (diff)
downloadlinux-2dcd9c71c1ffa9a036e09047f60e08383bb0abb6.tar.xz
Merge tag 'trace-v4.15' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace
Pull tracing updates from - allow module init functions to be traced - clean up some unused or not used by config events (saves space) - clean up of trace histogram code - add support for preempt and interrupt enabled/disable events - other various clean ups * tag 'trace-v4.15' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace: (30 commits) tracing, thermal: Hide cpu cooling trace events when not in use tracing, thermal: Hide devfreq trace events when not in use ftrace: Kill FTRACE_OPS_FL_PER_CPU perf/ftrace: Small cleanup perf/ftrace: Fix function trace events perf/ftrace: Revert ("perf/ftrace: Fix double traces of perf on ftrace:function") tracing, dma-buf: Remove unused trace event dma_fence_annotate_wait_on tracing, memcg, vmscan: Hide trace events when not in use tracing/xen: Hide events that are not used when X86_PAE is not defined tracing: mark trace_test_buffer as __maybe_unused printk: Remove superfluous memory barriers from printk_safe ftrace: Clear hashes of stale ips of init memory tracing: Add support for preempt and irq enable/disable events tracing: Prepare to add preempt and irq trace events ftrace/kallsyms: Have /proc/kallsyms show saved mod init functions ftrace: Add freeing algorithm to free ftrace_mod_maps ftrace: Save module init functions kallsyms symbols for tracing ftrace: Allow module init functions to be traced ftrace: Add a ftrace_free_mem() function for modules to use tracing: Reimplement log2 ...
Diffstat (limited to 'kernel/printk')
-rw-r--r--kernel/printk/printk_safe.c15
1 files changed, 8 insertions, 7 deletions
diff --git a/kernel/printk/printk_safe.c b/kernel/printk/printk_safe.c
index 3cdaeaef9ce1..724d9292d4b9 100644
--- a/kernel/printk/printk_safe.c
+++ b/kernel/printk/printk_safe.c
@@ -39,7 +39,7 @@
* There are situations when we want to make sure that all buffers
* were handled or when IRQs are blocked.
*/
-static int printk_safe_irq_ready;
+static int printk_safe_irq_ready __read_mostly;
#define SAFE_LOG_BUF_LEN ((1 << CONFIG_PRINTK_SAFE_LOG_BUF_SHIFT) - \
sizeof(atomic_t) - \
@@ -63,11 +63,8 @@ static DEFINE_PER_CPU(struct printk_safe_seq_buf, nmi_print_seq);
/* Get flushed in a more safe context. */
static void queue_flush_work(struct printk_safe_seq_buf *s)
{
- if (printk_safe_irq_ready) {
- /* Make sure that IRQ work is really initialized. */
- smp_rmb();
+ if (printk_safe_irq_ready)
irq_work_queue(&s->work);
- }
}
/*
@@ -398,8 +395,12 @@ void __init printk_safe_init(void)
#endif
}
- /* Make sure that IRQ works are initialized before enabling. */
- smp_wmb();
+ /*
+ * In the highly unlikely event that a NMI were to trigger at
+ * this moment. Make sure IRQ work is set up before this
+ * variable is set.
+ */
+ barrier();
printk_safe_irq_ready = 1;
/* Flush pending messages that did not have scheduled IRQ works. */