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Subject[for-next][PATCH 02/16] tracing: Remove size restriction on hist trigger cmd error logging
From: Tom Zanussi <zanussi@kernel.org>

Currently, hist trigger command error strings are restricted to a
length of MAX_FILTER_STR_VAL (256), which is too short for some
commands already seen in the wild (with cmd strings longer than that
showing up truncated in err_log).

Remove the restriction so that no hist trigger command error string is
ever truncated.

Link: https://lkml.kernel.org/r/0f9d46407222eaf6632cd3b417bc50a11f401b71.1643399022.git.zanussi@kernel.org

Signed-off-by: Tom Zanussi <zanussi@kernel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
---
kernel/trace/trace_events_hist.c | 30 +++++++++++++++++++++++-------
1 file changed, 23 insertions(+), 7 deletions(-)

diff --git a/kernel/trace/trace_events_hist.c b/kernel/trace/trace_events_hist.c
index ada87bfb5bb8..5e8970624bce 100644
--- a/kernel/trace/trace_events_hist.c
+++ b/kernel/trace/trace_events_hist.c
@@ -727,11 +727,16 @@ static struct track_data *track_data_alloc(unsigned int key_len,
return data;
}

-static char last_cmd[MAX_FILTER_STR_VAL];
+#define HIST_PREFIX "hist:"
+
+static char *last_cmd;
static char last_cmd_loc[MAX_FILTER_STR_VAL];

static int errpos(char *str)
{
+ if (!str || !last_cmd)
+ return 0;
+
return err_pos(last_cmd, str);
}

@@ -739,12 +744,19 @@ static void last_cmd_set(struct trace_event_file *file, char *str)
{
const char *system = NULL, *name = NULL;
struct trace_event_call *call;
+ int len = 0;

if (!str)
return;

- strcpy(last_cmd, "hist:");
- strncat(last_cmd, str, MAX_FILTER_STR_VAL - 1 - sizeof("hist:"));
+ len += sizeof(HIST_PREFIX) + strlen(str) + 1;
+ kfree(last_cmd);
+ last_cmd = kzalloc(len, GFP_KERNEL);
+ if (!last_cmd)
+ return;
+
+ strcpy(last_cmd, HIST_PREFIX);
+ strncat(last_cmd, str, len - sizeof(HIST_PREFIX));

if (file) {
call = file->event_call;
@@ -757,18 +769,22 @@ static void last_cmd_set(struct trace_event_file *file, char *str)
}

if (system)
- snprintf(last_cmd_loc, MAX_FILTER_STR_VAL, "hist:%s:%s", system, name);
+ snprintf(last_cmd_loc, MAX_FILTER_STR_VAL, HIST_PREFIX "%s:%s", system, name);
}

-static void hist_err(struct trace_array *tr, u8 err_type, u8 err_pos)
+static void hist_err(struct trace_array *tr, u8 err_type, u16 err_pos)
{
+ if (!last_cmd)
+ return;
+
tracing_log_err(tr, last_cmd_loc, last_cmd, err_text,
err_type, err_pos);
}

static void hist_err_clear(void)
{
- last_cmd[0] = '\0';
+ if (last_cmd)
+ last_cmd[0] = '\0';
last_cmd_loc[0] = '\0';
}

@@ -5610,7 +5626,7 @@ static int event_hist_trigger_print(struct seq_file *m,
bool have_var = false;
unsigned int i;

- seq_puts(m, "hist:");
+ seq_puts(m, HIST_PREFIX);

if (data->name)
seq_printf(m, "%s:", data->name);
--
2.34.1
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