From: "Steven Rostedt (Red Hat)" <rostedt@xxxxxxxxxxx> commit 8d58e99af5980d444948720977b0976455885391 upstream. The seq_buf functions are rather useful outside of tracing. Instead of having it be dependent on CONFIG_TRACING, move the code into lib/ and allow other users to have access to it even when tracing is not configured. The seq_buf utility is similar to the seq_file utility, but instead of writing sending data back up to userland, it writes it into a buffer defined at seq_buf_init(). This allows us to send a descriptor around that writes printf() formatted strings into it that can be retrieved later. It is currently used by the tracing facility for such things like trace events to convert its binary saved data in the ring buffer into an ASCII human readable context to be displayed in /sys/kernel/debug/trace. It can also be used for doing NMI prints safely from NMI context into the seq_buf and retrieved later and dumped to printk() safely. Doing printk() from an NMI context is dangerous because an NMI can preempt a current printk() and deadlock on it. Link: http://lkml.kernel.org/p/20140619213952.058255809@xxxxxxxxxxx Tested-by: Jiri Kosina <jkosina@xxxxxxx> Acked-by: Jiri Kosina <jkosina@xxxxxxx> Reviewed-by: Petr Mladek <pmladek@xxxxxxx> [wanglong: backport to 3.10 stable - adjust context ] Signed-off-by: Wang Long <long.wanglong@xxxxxxxxxx> Signed-off-by: Steven Rostedt <rostedt@xxxxxxxxxxx> --- kernel/trace/Makefile | 1 - lib/Makefile | 2 +- {kernel/trace => lib}/seq_buf.c | 0 3 files changed, 1 insertion(+), 2 deletions(-) rename {kernel/trace => lib}/seq_buf.c (100%) diff --git a/kernel/trace/Makefile b/kernel/trace/Makefile index cfb86f1..d7e2068 100644 --- a/kernel/trace/Makefile +++ b/kernel/trace/Makefile @@ -27,7 +27,6 @@ obj-$(CONFIG_RING_BUFFER_BENCHMARK) += ring_buffer_benchmark.o obj-$(CONFIG_TRACING) += trace.o obj-$(CONFIG_TRACING) += trace_output.o -obj-$(CONFIG_TRACING) += seq_buf.o obj-$(CONFIG_TRACING) += trace_stat.o obj-$(CONFIG_TRACING) += trace_printk.o obj-$(CONFIG_CONTEXT_SWITCH_TRACER) += trace_sched_switch.o diff --git a/lib/Makefile b/lib/Makefile index 9efe480..4ecd2e4 100644 --- a/lib/Makefile +++ b/lib/Makefile @@ -13,7 +13,7 @@ lib-y := ctype.o string.o vsprintf.o cmdline.o \ sha1.o md5.o irq_regs.o reciprocal_div.o argv_split.o \ proportions.o flex_proportions.o prio_heap.o ratelimit.o show_mem.o \ is_single_threaded.o plist.o decompress.o kobject_uevent.o \ - earlycpio.o + earlycpio.o seq_buf.o obj-$(CONFIG_ARCH_HAS_DEBUG_STRICT_USER_COPY_CHECKS) += usercopy.o lib-$(CONFIG_MMU) += ioremap.o diff --git a/kernel/trace/seq_buf.c b/lib/seq_buf.c similarity index 100% rename from kernel/trace/seq_buf.c rename to lib/seq_buf.c -- 1.8.3.4 -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html