Re: [PATCH] tracing: Replace all non-returning strlcpy with strscpy

From: Azeem Shaikh
Date: Tue May 16 2023 - 10:46:21 EST


Thanks for the review.

>
> > kernel/trace/trace.c | 8 ++++----
> > kernel/trace/trace_events.c | 4 ++--
> > kernel/trace/trace_events_inject.c | 4 ++--
> > kernel/trace/trace_kprobe.c | 2 +-
> > kernel/trace/trace_probe.c | 2 +-
> > 10 files changed, 39 insertions(+), 43 deletions(-)
> >
> > diff --git a/include/trace/events/fib.h b/include/trace/events/fib.h
> > index 76297ecd4935..20b914250ce9 100644
> > --- a/include/trace/events/fib.h
> > +++ b/include/trace/events/fib.h
> > @@ -65,7 +65,7 @@ TRACE_EVENT(fib_table_lookup,
> > }
> >
> > dev = nhc ? nhc->nhc_dev : NULL;
> > - strlcpy(__entry->name, dev ? dev->name : "-", IFNAMSIZ);
> > + strscpy(__entry->name, dev ? dev->name : "-", IFNAMSIZ);
> >
> > if (nhc) {
> > if (nhc->nhc_gw_family == AF_INET) {
> > diff --git a/include/trace/events/fib6.h b/include/trace/events/fib6.h
> > index 4d3e607b3cde..5d7ee2610728 100644
> > --- a/include/trace/events/fib6.h
> > +++ b/include/trace/events/fib6.h
> > @@ -63,7 +63,7 @@ TRACE_EVENT(fib6_table_lookup,
> > }
> >
> > if (res->nh && res->nh->fib_nh_dev) {
> > - strlcpy(__entry->name, res->nh->fib_nh_dev->name, IFNAMSIZ);
> > + strscpy(__entry->name, res->nh->fib_nh_dev->name, IFNAMSIZ);
> > } else {
> > strcpy(__entry->name, "-");
> > }
> > diff --git a/include/trace/events/kyber.h b/include/trace/events/kyber.h
> > index bf7533f171ff..d4db2fa60e7b 100644
> > --- a/include/trace/events/kyber.h
> > +++ b/include/trace/events/kyber.h
> > @@ -21,8 +21,8 @@ TRACE_EVENT(kyber_latency,
> >
> > TP_STRUCT__entry(
> > __field( dev_t, dev )
> > - __array( char, domain, DOMAIN_LEN )
> > - __array( char, type, LATENCY_TYPE_LEN )
> > + __string( domain, domain )
> > + __string( type, type )
>
> Note, __string() adds a little bit more overhead. If the length is small
> enough (like 16 or 8, as the above are) then it is more efficient in both
> speed and size of the ring buffer to use the hard coded array, and not use
> the dynamic string.
>
> NACK on the above change.
>

Yeah I realized a little too late that these changes will have
performance overhead. Will remove.

>
> The below changes can be sent as its own patch, and I can take it.
>
> -- Steve

Thanks. Sent out a v2 for the below.


>
> > diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
> > index ebc59781456a..28ccd0c9bdf0 100644
> > --- a/kernel/trace/trace.c
> > +++ b/kernel/trace/trace.c
> > @@ -196,7 +196,7 @@ static int boot_snapshot_index;
> >
> > static int __init set_cmdline_ftrace(char *str)
> > {
> > - strlcpy(bootup_tracer_buf, str, MAX_TRACER_SIZE);
> > + strscpy(bootup_tracer_buf, str, MAX_TRACER_SIZE);
> > default_bootup_tracer = bootup_tracer_buf;
> > /* We are using ftrace early, expand it */
> > ring_buffer_expanded = true;
> > @@ -281,7 +281,7 @@ static char trace_boot_options_buf[MAX_TRACER_SIZE] __initdata;
> >
> > static int __init set_trace_boot_options(char *str)
> > {
> > - strlcpy(trace_boot_options_buf, str, MAX_TRACER_SIZE);
> > + strscpy(trace_boot_options_buf, str, MAX_TRACER_SIZE);
> > return 1;
> > }
> > __setup("trace_options=", set_trace_boot_options);
> > @@ -291,7 +291,7 @@ static char *trace_boot_clock __initdata;
> >
> > static int __init set_trace_boot_clock(char *str)
> > {
> > - strlcpy(trace_boot_clock_buf, str, MAX_TRACER_SIZE);
> > + strscpy(trace_boot_clock_buf, str, MAX_TRACER_SIZE);
> > trace_boot_clock = trace_boot_clock_buf;
> > return 1;
> > }
> > @@ -2521,7 +2521,7 @@ static void __trace_find_cmdline(int pid, char comm[])
> > if (map != NO_CMDLINE_MAP) {
> > tpid = savedcmd->map_cmdline_to_pid[map];
> > if (tpid == pid) {
> > - strlcpy(comm, get_saved_cmdlines(map), TASK_COMM_LEN);
> > + strscpy(comm, get_saved_cmdlines(map), TASK_COMM_LEN);
> > return;
> > }
> > }
> > diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c
> > index 654ffa40457a..dc83a259915b 100644
> > --- a/kernel/trace/trace_events.c
> > +++ b/kernel/trace/trace_events.c
> > @@ -2831,7 +2831,7 @@ static __init int setup_trace_triggers(char *str)
> > char *buf;
> > int i;
> >
> > - strlcpy(bootup_trigger_buf, str, COMMAND_LINE_SIZE);
> > + strscpy(bootup_trigger_buf, str, COMMAND_LINE_SIZE);
> > ring_buffer_expanded = true;
> > disable_tracing_selftest("running event triggers");
> >
> > @@ -3621,7 +3621,7 @@ static char bootup_event_buf[COMMAND_LINE_SIZE] __initdata;
> >
> > static __init int setup_trace_event(char *str)
> > {
> > - strlcpy(bootup_event_buf, str, COMMAND_LINE_SIZE);
> > + strscpy(bootup_event_buf, str, COMMAND_LINE_SIZE);
> > ring_buffer_expanded = true;
> > disable_tracing_selftest("running event tracing");
> >
> > diff --git a/kernel/trace/trace_events_inject.c b/kernel/trace/trace_events_inject.c
> > index d6b4935a78c0..abe805d471eb 100644
> > --- a/kernel/trace/trace_events_inject.c
> > +++ b/kernel/trace/trace_events_inject.c
> > @@ -217,7 +217,7 @@ static int parse_entry(char *str, struct trace_event_call *call, void **pentry)
> > char *addr = (char *)(unsigned long) val;
> >
> > if (field->filter_type == FILTER_STATIC_STRING) {
> > - strlcpy(entry + field->offset, addr, field->size);
> > + strscpy(entry + field->offset, addr, field->size);
> > } else if (field->filter_type == FILTER_DYN_STRING ||
> > field->filter_type == FILTER_RDYN_STRING) {
> > int str_len = strlen(addr) + 1;
> > @@ -232,7 +232,7 @@ static int parse_entry(char *str, struct trace_event_call *call, void **pentry)
> > }
> > entry = *pentry;
> >
> > - strlcpy(entry + (entry_size - str_len), addr, str_len);
> > + strscpy(entry + (entry_size - str_len), addr, str_len);
> > str_item = (u32 *)(entry + field->offset);
> > if (field->filter_type == FILTER_RDYN_STRING)
> > str_loc -= field->offset + field->size;
> > diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c
> > index 59cda19a9033..1b3fa7b854aa 100644
> > --- a/kernel/trace/trace_kprobe.c
> > +++ b/kernel/trace/trace_kprobe.c
> > @@ -30,7 +30,7 @@ static char kprobe_boot_events_buf[COMMAND_LINE_SIZE] __initdata;
> >
> > static int __init set_kprobe_boot_events(char *str)
> > {
> > - strlcpy(kprobe_boot_events_buf, str, COMMAND_LINE_SIZE);
> > + strscpy(kprobe_boot_events_buf, str, COMMAND_LINE_SIZE);
> > disable_tracing_selftest("running kprobe events");
> >
> > return 1;
> > diff --git a/kernel/trace/trace_probe.c b/kernel/trace/trace_probe.c
> > index 2d2616678295..73055ba8d8ef 100644
> > --- a/kernel/trace/trace_probe.c
> > +++ b/kernel/trace/trace_probe.c
> > @@ -254,7 +254,7 @@ int traceprobe_parse_event_name(const char **pevent, const char **pgroup,
> > trace_probe_log_err(offset, GROUP_TOO_LONG);
> > return -EINVAL;
> > }
> > - strlcpy(buf, event, slash - event + 1);
> > + strscpy(buf, event, slash - event + 1);
> > if (!is_good_system_name(buf)) {
> > trace_probe_log_err(offset, BAD_GROUP_NAME);
> > return -EINVAL;
>