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| author | Steven Rostedt (Red Hat) <rostedt@goodmis.org> | 2014-06-19 17:33:30 -0400 |
|---|---|---|
| committer | Steven Rostedt <rostedt@goodmis.org> | 2014-11-19 22:01:20 -0500 |
| commit | 8d58e99af5980d444948720977b0976455885391 (patch) | |
| tree | 1c40f6ed895112fb34b139a8bcd0e49d321fbd22 | |
| parent | 2448913ed2aa7a7424d9b9ca79861d13c746a3f1 (diff) | |
| download | linux-8d58e99af5980d444948720977b0976455885391.tar.bz2 | |
seq_buf: Move the seq_buf code to lib/
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@goodmis.org
Tested-by: Jiri Kosina <jkosina@suse.cz>
Acked-by: Jiri Kosina <jkosina@suse.cz>
Reviewed-by: Petr Mladek <pmladek@suse.cz>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
| -rw-r--r-- | kernel/trace/Makefile | 1 | ||||
| -rw-r--r-- | lib/Makefile | 2 | ||||
| -rw-r--r-- | lib/seq_buf.c (renamed from kernel/trace/seq_buf.c) | 0 |
3 files changed, 1 insertions, 2 deletions
diff --git a/kernel/trace/Makefile b/kernel/trace/Makefile index edc98c72a634..67d6369ddf83 100644 --- a/kernel/trace/Makefile +++ b/kernel/trace/Makefile @@ -29,7 +29,6 @@ obj-$(CONFIG_RING_BUFFER_BENCHMARK) += ring_buffer_benchmark.o obj-$(CONFIG_TRACING) += trace.o obj-$(CONFIG_TRACING) += trace_output.o obj-$(CONFIG_TRACING) += trace_seq.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 7512dc978f18..a1aa1e81ed36 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 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 index 4eedfedb9e31..4eedfedb9e31 100644 --- a/kernel/trace/seq_buf.c +++ b/lib/seq_buf.c |