tracing: Use EVENT_NULL_STR macro instead of open coding "(null)"

The TRACE_EVENT macros has some dependency if a __string() field is NULL,
where it will save "(null)" as the string. This string is also used by
__assign_str(). It's better to create a single macro instead of having
something that will not be caught by the compiler if there is an
unfortunate typo.

Link: https://lore.kernel.org/linux-trace-kernel/20240222211443.106216915@goodmis.org
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
Cc: Chuck Lever <chuck.lever@oracle.com>
Suggested-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>

diff --git a/include/linux/trace_events.h b/include/linux/trace_events.h
index fc6d0af56bb172c4c5356404b19160568c751d4b..6f9bdfb09d1da5cd0f6dc84635380f4f49156352 100644 (file)
--- a/include/linux/trace_events.h
+++ b/include/linux/trace_events.h
@@ -17,6 +17,9 @@ struct dentry;
 struct bpf_prog;
 union bpf_attr;
 
+/* Used for event string fields when they are NULL */
+#define EVENT_NULL_STR         "(null)"
+
 const char *trace_print_flags_seq(struct trace_seq *p, const char *delim,
                                  unsigned long flags,
                                  const struct trace_print_flags *flag_array);

diff --git a/include/trace/events/sunrpc.h b/include/trace/events/sunrpc.h
index cdd3a45e6003aa5791932261757d32f1287747de..ce6a85b82afa0cb5811db1c7a35094c8c96d6bb0 100644 (file)
--- a/include/trace/events/sunrpc.h
+++ b/include/trace/events/sunrpc.h
@@ -1327,18 +1327,18 @@ TRACE_EVENT(xs_stream_read_data,
                __field(ssize_t, err)
                __field(size_t, total)
                __string(addr, xprt ? xprt->address_strings[RPC_DISPLAY_ADDR] :
-                               "(null)")
+                               EVENT_NULL_STR)
                __string(port, xprt ? xprt->address_strings[RPC_DISPLAY_PORT] :
-                               "(null)")
+                               EVENT_NULL_STR)
        ),
 
        TP_fast_assign(
                __entry->err = err;
                __entry->total = total;
                __assign_str(addr, xprt ?
-                       xprt->address_strings[RPC_DISPLAY_ADDR] : "(null)");
+                       xprt->address_strings[RPC_DISPLAY_ADDR] : EVENT_NULL_STR);
                __assign_str(port, xprt ?
-                       xprt->address_strings[RPC_DISPLAY_PORT] : "(null)");
+                       xprt->address_strings[RPC_DISPLAY_PORT] : EVENT_NULL_STR);
        ),
 
        TP_printk("peer=[%s]:%s err=%zd total=%zu", __get_str(addr),
@@ -1783,7 +1783,7 @@ TRACE_EVENT(svc_process,
                __string(service, name)
                __string(procedure, svc_proc_name(rqst))
                __string(addr, rqst->rq_xprt ?
-                        rqst->rq_xprt->xpt_remotebuf : "(null)")
+                        rqst->rq_xprt->xpt_remotebuf : EVENT_NULL_STR)
        ),
 
        TP_fast_assign(
@@ -1793,7 +1793,7 @@ TRACE_EVENT(svc_process,
                __assign_str(service, name);
                __assign_str(procedure, svc_proc_name(rqst));
                __assign_str(addr, rqst->rq_xprt ?
-                            rqst->rq_xprt->xpt_remotebuf : "(null)");
+                            rqst->rq_xprt->xpt_remotebuf : EVENT_NULL_STR);
        ),
 
        TP_printk("addr=%s xid=0x%08x service=%s vers=%u proc=%s",

diff --git a/include/trace/stages/stage5_get_offsets.h b/include/trace/stages/stage5_get_offsets.h
index 20b801ed3fd44567d7e95745d952e6975647fde3..e6b96608f45232d5873cf2a0c501986a854897e1 100644 (file)
--- a/include/trace/stages/stage5_get_offsets.h
+++ b/include/trace/stages/stage5_get_offsets.h
@@ -47,7 +47,7 @@
 
 #undef __string
 #define __string(item, src) __dynamic_array(char, item,                        \
-                   strlen((const char *)(src) ? : "(null)") + 1)       \
+                   strlen((const char *)(src) ? : EVENT_NULL_STR) + 1) \
        __data_offsets->item##_ptr_ = src;
 
 #undef __string_len
@@ -70,7 +70,7 @@
 
 #undef __rel_string
 #define __rel_string(item, src) __rel_dynamic_array(char, item,                \
-                   strlen((const char *)(src) ? : "(null)") + 1)       \
+                   strlen((const char *)(src) ? : EVENT_NULL_STR) + 1) \
        __data_offsets->item##_ptr_ = src;
 
 #undef __rel_string_len

diff --git a/include/trace/stages/stage6_event_callback.h b/include/trace/stages/stage6_event_callback.h
index 38732855eadb8182215359670e516dfd900a2019..2bfd49713b421bc8235b0e3c26b98a73590ce0b9 100644 (file)
--- a/include/trace/stages/stage6_event_callback.h
+++ b/include/trace/stages/stage6_event_callback.h
@@ -32,14 +32,14 @@
 
 #undef __assign_str
 #define __assign_str(dst, src)                                         \
-       memcpy(__get_str(dst), __data_offsets.dst##_ptr_ ? : "(null)",  \
+       memcpy(__get_str(dst), __data_offsets.dst##_ptr_ ? : EVENT_NULL_STR, \
               __get_dynamic_array_len(dst))
 
 #undef __assign_str_len
 #define __assign_str_len(dst, src, len)                                        \
        do {                                                            \
                memcpy(__get_str(dst),                                  \
-                      __data_offsets.dst##_ptr_ ? : "(null)", len);    \
+                      __data_offsets.dst##_ptr_ ? : EVENT_NULL_STR, len); \
                __get_str(dst)[len] = '\0';                             \
        } while(0)
 
@@ -94,14 +94,14 @@
 
 #undef __assign_rel_str
 #define __assign_rel_str(dst, src)                                     \
-       memcpy(__get_rel_str(dst), __data_offsets.dst##_ptr_ ? : "(null)", \
+       memcpy(__get_rel_str(dst), __data_offsets.dst##_ptr_ ? : EVENT_NULL_STR, \
               __get_rel_dynamic_array_len(dst))
 
 #undef __assign_rel_str_len
 #define __assign_rel_str_len(dst, src, len)                            \
        do {                                                            \
                memcpy(__get_rel_str(dst),                              \
-                      __data_offsets.dst##_ptr_ ? : "(null)", len);    \
+                      __data_offsets.dst##_ptr_ ? : EVENT_NULL_STR, len); \
                __get_rel_str(dst)[len] = '\0';                         \
        } while (0)