On Wed, 19 Dec 2018 13:46:49 -0600 Tom Zanussi <[email protected]> wrote:
> Yeah, I had considered it but wasn't sure it was worth it. Since > you're suggesting it is, I can send another patch on top of these, or > feel free if you want to too. ;-) > Here, want to ack/review it? -- Steve >From 664457f5cc776aa624502bc628285ea6d70ac8c9 Mon Sep 17 00:00:00 2001 From: "Steven Rostedt (VMware)" <[email protected]> Date: Wed, 19 Dec 2018 15:13:33 -0500 Subject: [PATCH] tracing: Add strncmp_const() macro to prevent typos and cut paste errors The trace_events_hist.c file has a lot of strncmp()s of the form: if (strncmp(str, "constant", sizeof("constant") - 1) == 0) To prevent typos and errors with the constant string being different from the string use in sizeof(), and also to condense the code, add a macro that does this: #define strncmp_const(str, str_const) \ strncmp(str, str_const, sizeof(str_const) - 1) Signed-off-by: Steven Rostedt (VMware) <[email protected]> --- kernel/trace/trace_events_hist.c | 32 ++++++++++++++++++-------------- 1 file changed, 18 insertions(+), 14 deletions(-) diff --git a/kernel/trace/trace_events_hist.c b/kernel/trace/trace_events_hist.c index c5448c103770..40e76053d3d7 100644 --- a/kernel/trace/trace_events_hist.c +++ b/kernel/trace/trace_events_hist.c @@ -22,6 +22,10 @@ #define STR_VAR_LEN_MAX 32 /* must be multiple of sizeof(u64) */ +/* Safe way to compare string constants (from typos and cut and paste errors) */ +#define strncmp_const(str, str_const) \ + strncmp(str, str_const, sizeof(str_const) - 1) + struct hist_field; typedef u64 (*hist_field_fn_t) (struct hist_field *field, @@ -1881,8 +1885,8 @@ static int parse_action(char *str, struct hist_trigger_attrs *attrs) if (attrs->n_actions >= HIST_ACTIONS_MAX) return ret; - if ((strncmp(str, "onmatch(", sizeof("onmatch(") - 1) == 0) || - (strncmp(str, "onmax(", sizeof("onmax(") - 1) == 0)) { + if ((strncmp_const(str, "onmatch(") == 0) || + (strncmp_const(str, "onmax(") == 0)) { attrs->action_str[attrs->n_actions] = kstrdup(str, GFP_KERNEL); if (!attrs->action_str[attrs->n_actions]) { ret = -ENOMEM; @@ -1899,34 +1903,34 @@ static int parse_assignment(char *str, struct hist_trigger_attrs *attrs) { int ret = 0; - if ((strncmp(str, "key=", sizeof("key=") - 1) == 0) || - (strncmp(str, "keys=", sizeof("keys=") - 1) == 0)) { + if ((strncmp_const(str, "key=") == 0) || + (strncmp_const(str, "keys=") == 0)) { attrs->keys_str = kstrdup(str, GFP_KERNEL); if (!attrs->keys_str) { ret = -ENOMEM; goto out; } - } else if ((strncmp(str, "val=", sizeof("val=") - 1) == 0) || - (strncmp(str, "vals=", sizeof("vals=") - 1) == 0) || - (strncmp(str, "values=", sizeof("values=") - 1) == 0)) { + } else if ((strncmp_const(str, "val=") == 0) || + (strncmp_const(str, "vals=") == 0) || + (strncmp_const(str, "values=") == 0)) { attrs->vals_str = kstrdup(str, GFP_KERNEL); if (!attrs->vals_str) { ret = -ENOMEM; goto out; } - } else if (strncmp(str, "sort=", sizeof("sort=") - 1) == 0) { + } else if (strncmp_const(str, "sort=") == 0) { attrs->sort_key_str = kstrdup(str, GFP_KERNEL); if (!attrs->sort_key_str) { ret = -ENOMEM; goto out; } - } else if (strncmp(str, "name=", sizeof("name=") - 1) == 0) { + } else if (strncmp_const(str, "name=") == 0) { attrs->name = kstrdup(str, GFP_KERNEL); if (!attrs->name) { ret = -ENOMEM; goto out; } - } else if (strncmp(str, "clock=", sizeof("clock=") - 1) == 0) { + } else if (strncmp_const(str, "clock=") == 0) { strsep(&str, "="); if (!str) { ret = -EINVAL; @@ -1939,7 +1943,7 @@ static int parse_assignment(char *str, struct hist_trigger_attrs *attrs) ret = -ENOMEM; goto out; } - } else if (strncmp(str, "size=", sizeof("size=") - 1) == 0) { + } else if (strncmp_const(str, "size=") == 0) { int map_bits = parse_map_size(str); if (map_bits < 0) { @@ -3558,7 +3562,7 @@ static struct action_data *onmax_parse(char *str) if (!onmax_fn_name || !str) goto free; - if (strncmp(onmax_fn_name, "save", sizeof("save") - 1) == 0) { + if (strncmp_const(onmax_fn_name, "save") == 0) { char *params = strsep(&str, ")"); if (!params) { @@ -4346,7 +4350,7 @@ static int parse_actions(struct hist_trigger_data *hist_data) for (i = 0; i < hist_data->attrs->n_actions; i++) { str = hist_data->attrs->action_str[i]; - if (strncmp(str, "onmatch(", sizeof("onmatch(") - 1) == 0) { + if (strncmp_const(str, "onmatch(") == 0) { char *action_str = str + sizeof("onmatch(") - 1; data = onmatch_parse(tr, action_str); @@ -4355,7 +4359,7 @@ static int parse_actions(struct hist_trigger_data *hist_data) break; } data->fn = action_trace; - } else if (strncmp(str, "onmax(", sizeof("onmax(") - 1) == 0) { + } else if (strncmp_const(str, "onmax(") == 0) { char *action_str = str + sizeof("onmax(") - 1; data = onmax_parse(action_str); -- 2.19.1
