From: Steven Rostedt <rostedt@goodmis.org>
To: linux-trace-devel@vger.kernel.org
Cc: Sameeruddin shaik <sameeruddin.shaik8@gmail.com>
Subject: [PATCH 2/4] libtracefs: Allow filter be NULL if RESET flag is set
Date: Tue, 30 Mar 2021 14:33:26 -0400 [thread overview]
Message-ID: <20210330183546.058728551@goodmis.org> (raw)
In-Reply-To: 20210330183324.709017776@goodmis.org
From: "Steven Rostedt (VMware)" <rostedt@goodmis.org>
If the TRACEFS_FL_RESET flag is set, and the instance has yet to be
opened, the filter parameter can be NULL. This will allow simply resetting
the filter (clearing it).
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
---
Documentation/libtracefs-function-filter.txt | 27 ++++++++++++++------
src/tracefs-tools.c | 15 ++++++++---
2 files changed, 31 insertions(+), 11 deletions(-)
diff --git a/Documentation/libtracefs-function-filter.txt b/Documentation/libtracefs-function-filter.txt
index a022a2196b75..a4218b75deea 100644
--- a/Documentation/libtracefs-function-filter.txt
+++ b/Documentation/libtracefs-function-filter.txt
@@ -37,6 +37,12 @@ not a period, but will match any one character. To force a regular
expression, either prefix _filter_ with a '^' or append it with a '$' as
the _filter_ does complete matches of the functions anyway.
+The _filter_ may be NULL if a previous call to *tracefs_function_filter()* with
+the same _instance_ had *TRACEFS_FL_CONTINUE* set and this call does not. This is
+useful to simply commit the previous filters. It may also be NULL
+if *TRACEFS_FL_RESET* is set and the previous call did not have the same _instance_
+and *TRACEFS_FL_CONTINUE* set. This is useful to just clear the filter.
+
FLAGS
-----
@@ -102,20 +108,25 @@ int main(int argc, char *argv[])
{
struct tracefs_instance *inst = tracefs_instance_create(INST);
int ret;
- int reset = TRACEFS_FL_RESET;
int i;
if (!inst) {
/* Error creating new trace instance */
}
+ /* First reset the filter */
+ ret = tracefs_function_filter(inst, NULL, NULL,
+ TRACEFS_FL_RESET | TRACEFS_FL_CONTINUE);
+ if (ret) {
+ printf("Failed to reset the filter\n");
+ /* Make sure it is closed, -1 means filter was started */
+ if (ret < 0)
+ tracefs_function_filter(inst, NULL, NULL, 0);
+ }
+
for (i = 0; filters[i]; i++) {
- /*
- * Only the first call can have TRACEFS_FL_RESET set
- * while TRACEFS_FL_CONTINUE is set.
- */
ret = tracefs_function_filter(inst, filters[i], NULL,
- reset | TRACEFS_FL_CONTINUE);
+ TRACEFS_FL_CONTINUE);
if (ret) {
if (errno == EINVAL)
@@ -123,7 +134,6 @@ int main(int argc, char *argv[])
else
printf("Failed writing %s\n", filters[i]);
}
- reset = 0;
}
ret = tracefs_function_filter(inst, "*", "ext4", 0);
@@ -133,8 +143,9 @@ int main(int argc, char *argv[])
tracefs_function_filter(inst, NULL, NULL, 0);
}
+ out:
tracefs_instance_destroy(inst);
- return 0;
+ return ret;
}
--
diff --git a/src/tracefs-tools.c b/src/tracefs-tools.c
index 5719ddf66982..a9a51beb02b2 100644
--- a/src/tracefs-tools.c
+++ b/src/tracefs-tools.c
@@ -794,6 +794,10 @@ int tracefs_function_filter(struct tracefs_instance *instance, const char *filte
close(*fd);
*fd = -1;
}
+ /* Also OK to call if reset flag is set */
+ if (reset)
+ goto open_file;
+
goto out;
}
@@ -804,6 +808,7 @@ int tracefs_function_filter(struct tracefs_instance *instance, const char *filte
if (ret)
goto out_free;
+ open_file:
ret = 1;
ftrace_filter_path = tracefs_instance_get_file(instance, TRACE_FILTER);
if (!ftrace_filter_path)
@@ -819,9 +824,13 @@ int tracefs_function_filter(struct tracefs_instance *instance, const char *filte
errno = 0;
- ret = write_func_list(*fd, func_list);
- if (ret > 0)
- ret = controlled_write(*fd, &func_filter, module);
+ ret = 0;
+
+ if (filter) {
+ ret = write_func_list(*fd, func_list);
+ if (ret > 0)
+ ret = controlled_write(*fd, &func_filter, module);
+ }
if (!cont) {
close(*fd);
--
2.30.1
next prev parent reply other threads:[~2021-03-30 18:44 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-30 18:33 [PATCH 0/4] libtracefs: More updates to tracefs_function_filter() Steven Rostedt
2021-03-30 18:33 ` [PATCH 1/4] libtracefs: Only allow RESET flag if file is not already opened Steven Rostedt
2021-03-30 18:33 ` Steven Rostedt [this message]
2021-03-30 18:33 ` [PATCH 3/4] libtracefs: Allow filter to be NULL if module is set in tracefs_function_filter() Steven Rostedt
2021-03-30 18:33 ` [PATCH 4/4] libtracefs: Add TRACEFS_FL_FUTURE flag for future module filtering Steven Rostedt
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