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authorSteven Rostedt (Red Hat) <rostedt@goodmis.org>2014-06-19 17:33:30 -0400
committerSteven Rostedt <rostedt@goodmis.org>2014-11-19 22:01:20 -0500
commit8d58e99af5980d444948720977b0976455885391 (patch)
tree1c40f6ed895112fb34b139a8bcd0e49d321fbd22
parent2448913ed2aa7a7424d9b9ca79861d13c746a3f1 (diff)
downloadlinux-8d58e99af5980d444948720977b0976455885391.tar.gz
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/Makefile1
-rw-r--r--lib/Makefile2
-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