On Tue, 9 May 2017 10:50:04 +0200 Vegard Nossum <vegard.nos...@oracle.com> wrote:
> When using trace_dump_stack() you currently just get a list of function > names. > > It can be very useful to know exactly where a call came from, especially > if there are multiple calls from one function to another. > > By switching trace_dump_stack() to use %pF we get the function name and > the offset, which can also be further processed to give exact line number > information, like this: > > <...>-1087 3.... 3270529us : <stack trace> > => pty_write+0x45/0x50 > => n_tty_write+0x358/0x470 > => tty_write+0x189/0x2f0 > => __vfs_write+0x23/0x120 > => vfs_write+0xb3/0x1b0 > => SyS_write+0x44/0xa0 > => entry_SYSCALL_64_fastpath+0x18/0xad > > $ scripts/faddr2line vmlinux tty_write+0x189/0x2f0 > tty_write+0x189/0x2f0: > do_tty_write at drivers/tty/tty_io.c:1174 > (inlined by) tty_write at drivers/tty/tty_io.c:1257 I prefer not to see it by default. If you want to see it: echo 1 > /sys/kernel/debug/tracing/options/sym-offset NACK. -- Steve > > Signed-off-by: Vegard Nossum <vegard.nos...@oracle.com> > --- > kernel/trace/trace_output.c | 4 +--- > 1 file changed, 1 insertion(+), 3 deletions(-) > > diff --git a/kernel/trace/trace_output.c b/kernel/trace/trace_output.c > index 02a4aeb22c47..879909efed33 100644 > --- a/kernel/trace/trace_output.c > +++ b/kernel/trace/trace_output.c > @@ -1073,9 +1073,7 @@ static enum print_line_t trace_stack_print(struct > trace_iterator *iter, > if (trace_seq_has_overflowed(s)) > break; > > - trace_seq_puts(s, " => "); > - seq_print_ip_sym(s, *p, flags); > - trace_seq_putc(s, '\n'); > + trace_seq_printf(s, " => %pF\n", (void *) *p); > } > > return trace_handle_return(s);
