[PATCH v2 2/2] [BUGFIX] perf probe: Fix --del option to delete events only with uprobe events

From: Masami Hiramatsu
Date: Wed Aug 13 2014 - 12:12:59 EST


Current perf probe --del doesn't work if only CONFIG_UPROBE_EVENTS=y
because it aborts when it fails to open kprobe_events file before
checking uprobe_events file.

This fixes --del option to delete dynamic events if it can open
either kprobe_events or uprobe_events. Only if it failed to open
both of them, it shows an error message and aborts.

Without this patch, if we run perf probe -d on the kernel configured
with CONFIG_KPROBE_EVENTS=n and CONFIG_UPROBE_EVENTS=y,

# perf probe -d \*
kprobe_events file does not exist - please rebuild kernel with CONFIG_KPROBE_EVENTS.
Error: Failed to delete events.

With this patch,

# perf probe -d \*
Removed event: probe_perf:alloc_event

Changes in v2:
- Use strerror_r instead of strerror.

Signed-off-by: Masami Hiramatsu <masami.hiramatsu.pt@xxxxxxxxxxx>
Cc: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
Cc: Paul Mackerras <paulus@xxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
---
tools/perf/util/probe-event.c | 49 ++++++++++++++++++++++-------------------
1 file changed, 26 insertions(+), 23 deletions(-)

diff --git a/tools/perf/util/probe-event.c b/tools/perf/util/probe-event.c
index 50aa7f0..443225c 100644
--- a/tools/perf/util/probe-event.c
+++ b/tools/perf/util/probe-event.c
@@ -1803,6 +1803,23 @@ static void print_open_warning(int err, bool is_kprobe)
strerror_r(-err, sbuf, sizeof(sbuf)));
}

+static void print_both_open_warning(int kerr, int uerr)
+{
+ /* Both kprobes and uprobes are disabled, warn it. */
+ if (kerr == -ENOTSUP && uerr == -ENOTSUP)
+ pr_warning("Debugfs is not mounted.\n");
+ else if (kerr == -ENOENT && uerr == -ENOENT)
+ pr_warning("Please rebuild kernel with CONFIG_KPROBE_EVENTS "
+ "or/and CONFIG_UPROBE_EVENTS.\n");
+ else {
+ char sbuf[128];
+ pr_warning("Failed to open kprobe events: %s.\n",
+ strerror_r(-kerr, sbuf, sizeof(sbuf)));
+ pr_warning("Failed to open uprobe events: %s.\n",
+ strerror_r(-uerr, sbuf, sizeof(sbuf)));
+ }
+}
+
static int open_probe_events(const char *trace_file, bool readwrite)
{
char buf[PATH_MAX];
@@ -1960,20 +1977,7 @@ int show_perf_probe_events(void)

up_fd = open_uprobe_events(false);
if (kp_fd < 0 && up_fd < 0) {
- /* Both kprobes and uprobes are disabled, warn it. */
- if (kp_fd == -ENOTSUP && up_fd == -ENOTSUP)
- pr_warning("Debugfs is not mounted.\n");
- else if (kp_fd == -ENOENT && up_fd == -ENOENT)
- pr_warning("Please rebuild kernel with "
- "CONFIG_KPROBE_EVENTS or/and "
- "CONFIG_UPROBE_EVENTS.\n");
- else {
- char sbuf[128];
- pr_warning("Failed to open kprobe events: %s.\n",
- strerror_r(-kp_fd, sbuf, sizeof(sbuf)));
- pr_warning("Failed to open uprobe events: %s.\n",
- strerror_r(-up_fd, sbuf, sizeof(sbuf)));
- }
+ print_both_open_warning(kp_fd, up_fd);
ret = kp_fd;
goto out;
}
@@ -2474,19 +2478,18 @@ int del_perf_probe_events(struct strlist *dellist)

/* Get current event names */
kfd = open_kprobe_events(true);
- if (kfd < 0) {
- print_open_warning(kfd, true);
- return kfd;
- }
+ if (kfd >= 0)
+ namelist = get_probe_trace_event_names(kfd, true);

- namelist = get_probe_trace_event_names(kfd, true);
ufd = open_uprobe_events(true);
-
- if (ufd < 0)
- print_open_warning(ufd, false);
- else
+ if (ufd >= 0)
unamelist = get_probe_trace_event_names(ufd, true);

+ if (kfd < 0 && ufd < 0) {
+ print_both_open_warning(kfd, ufd);
+ goto error;
+ }
+
if (namelist == NULL && unamelist == NULL)
goto error;


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