On Fri, 16 Dec 2016 16:22:25 +0000 David Howells <[email protected]> wrote:
> Steven Rostedt <[email protected]> wrote: > > > > Another feature that would be very nice to have is the ability to turn a > > > number into a string by direct array index rather than by table search or > > > serial ?: ternary operators. > > > > Which function are you talking about? > > See the attached patch that converts rxrpc's tracing from using string arrays > to using TRACE_DEFINE_ENUM so that utilities like crash's trace buffer > disassembler can find the string values. > > When __print_symbolic() is used, each set of strings is rendered as an array > of trace_print_flag structs which trace_print_symbols_seq() then iterates > over to find a match. > You mean to do something like this? (untested, not even compiled) -- Steve --- include/linux/trace_events.h | 6 ++++-- include/trace/trace_events.h | 10 ++++++---- kernel/trace/trace_output.c | 28 ++++++++++++++++++++++++---- 3 files changed, 34 insertions(+), 10 deletions(-) Index: linux-trace.git/include/linux/trace_events.h =================================================================== --- linux-trace.git.orig/include/linux/trace_events.h 2016-11-15 17:27:19.397749523 -0500 +++ linux-trace.git/include/linux/trace_events.h 2016-12-16 11:34:38.783424430 -0500 @@ -20,13 +20,15 @@ const char *trace_print_flags_seq(struct const struct trace_print_flags *flag_array); const char *trace_print_symbols_seq(struct trace_seq *p, unsigned long val, - const struct trace_print_flags *symbol_array); + const struct trace_print_flags *symbol_array, + unsigned long nr); #if BITS_PER_LONG == 32 const char *trace_print_symbols_seq_u64(struct trace_seq *p, unsigned long long val, const struct trace_print_flags_u64 - *symbol_array); + *symbol_array, + unsigned long long nr); #endif const char *trace_print_bitmask_seq(struct trace_seq *p, void *bitmask_ptr, Index: linux-trace.git/include/trace/trace_events.h =================================================================== --- linux-trace.git.orig/include/trace/trace_events.h 2016-12-16 11:29:39.599950900 -0500 +++ linux-trace.git/include/trace/trace_events.h 2016-12-16 11:30:39.927844742 -0500 @@ -279,8 +279,9 @@ TRACE_MAKE_SYSTEM_STR(); #define __print_symbolic(value, symbol_array...) \ ({ \ static const struct trace_print_flags symbols[] = \ - { symbol_array, { -1, NULL }}; \ - trace_print_symbols_seq(p, value, symbols); \ + { symbol_array}}; \ + trace_print_symbols_seq(p, value, symbols, \ + ARRAY_SIZE(symbols)); \ }) #undef __print_symbolic_u64 @@ -288,8 +289,9 @@ TRACE_MAKE_SYSTEM_STR(); #define __print_symbolic_u64(value, symbol_array...) \ ({ \ static const struct trace_print_flags_u64 symbols[] = \ - { symbol_array, { -1, NULL } }; \ - trace_print_symbols_seq_u64(p, value, symbols); \ + { symbol_array }; \ + trace_print_symbols_seq_u64(p, value, symbols, \ + ARRAY_SIZE(symbols)); \ }) #else #define __print_symbolic_u64(value, symbol_array...) \ Index: linux-trace.git/kernel/trace/trace_output.c =================================================================== --- linux-trace.git.orig/kernel/trace/trace_output.c 2016-12-14 10:33:28.581929129 -0500 +++ linux-trace.git/kernel/trace/trace_output.c 2016-12-16 11:36:41.695208145 -0500 @@ -99,12 +99,21 @@ EXPORT_SYMBOL(trace_print_flags_seq); const char * trace_print_symbols_seq(struct trace_seq *p, unsigned long val, - const struct trace_print_flags *symbol_array) + const struct trace_print_flags *symbol_array, + unsigned long nr) { int i; const char *ret = trace_seq_buffer_ptr(p); - for (i = 0; symbol_array[i].name; i++) { + /* A lot of arrays are simply enums that map to the array index */ + if (val < nr) { + if (val == symbol_array[val].mask) { + trace_seq_puts(p, symbol_array[val].name); + goto out; + } + } + + for (i = 0; i < nr; i++) { if (val != symbol_array[i].mask) continue; @@ -116,6 +125,7 @@ trace_print_symbols_seq(struct trace_seq if (ret == (const char *)(trace_seq_buffer_ptr(p))) trace_seq_printf(p, "0x%lx", val); + out: trace_seq_putc(p, 0); return ret; @@ -125,12 +135,21 @@ EXPORT_SYMBOL(trace_print_symbols_seq); #if BITS_PER_LONG == 32 const char * trace_print_symbols_seq_u64(struct trace_seq *p, unsigned long long val, - const struct trace_print_flags_u64 *symbol_array) + const struct trace_print_flags_u64 *symbol_array, + unsigned long long nr) { int i; const char *ret = trace_seq_buffer_ptr(p); - for (i = 0; symbol_array[i].name; i++) { + /* A lot of arrays are simply enums that map to the array index */ + if (val < nr) { + if (val == symbol_array[val].mask) { + trace_seq_puts(p, symbol_array[val].name); + goto out; + } + } + + for (i = 0; i < nr; i++) { if (val != symbol_array[i].mask) continue; @@ -142,6 +161,7 @@ trace_print_symbols_seq_u64(struct trace if (ret == (const char *)(trace_seq_buffer_ptr(p))) trace_seq_printf(p, "0x%llx", val); + out: trace_seq_putc(p, 0); return ret;
