[PATCH 4.9 57/60] stacktrace, lockdep: Fix address, newline ugliness

From: Greg Kroah-Hartman
Date: Mon Feb 13 2017 - 08:05:10 EST


4.9-stable review patch. If anyone has any objections, please let me know.

------------------

From: Omar Sandoval <osandov@xxxxxx>

commit bfeda41d06d85ad9d52f2413cfc2b77be5022f75 upstream.

Since KERN_CONT became meaningful again, lockdep stack traces have had
annoying extra newlines, like this:

[ 5.561122] -> #1 (B){+.+...}:
[ 5.561528]
[ 5.561532] [<ffffffff810d8873>] lock_acquire+0xc3/0x210
[ 5.562178]
[ 5.562181] [<ffffffff816f6414>] mutex_lock_nested+0x74/0x6d0
[ 5.562861]
[ 5.562880] [<ffffffffa01aa3c3>] init_btrfs_fs+0x21/0x196 [btrfs]
[ 5.563717]
[ 5.563721] [<ffffffff81000472>] do_one_initcall+0x52/0x1b0
[ 5.564554]
[ 5.564559] [<ffffffff811a3af6>] do_init_module+0x5f/0x209
[ 5.565357]
[ 5.565361] [<ffffffff81122f4d>] load_module+0x218d/0x2b80
[ 5.566020]
[ 5.566021] [<ffffffff81123beb>] SyS_finit_module+0xeb/0x120
[ 5.566694]
[ 5.566696] [<ffffffff816fd241>] entry_SYSCALL_64_fastpath+0x1f/0xc2

That's happening because each printk() call now gets printed on its own
line, and we do a separate call to print the spaces before the symbol.
Fix it by doing the printk() directly instead of using the
print_ip_sym() helper.

Additionally, the symbol address isn't very helpful, so let's get rid of
that, too. The final result looks like this:

[ 5.194518] -> #1 (B){+.+...}:
[ 5.195002] lock_acquire+0xc3/0x210
[ 5.195439] mutex_lock_nested+0x74/0x6d0
[ 5.196491] do_one_initcall+0x52/0x1b0
[ 5.196939] do_init_module+0x5f/0x209
[ 5.197355] load_module+0x218d/0x2b80
[ 5.197792] SyS_finit_module+0xeb/0x120
[ 5.198251] entry_SYSCALL_64_fastpath+0x1f/0xc2

Suggested-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Omar Sandoval <osandov@xxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: kernel-team@xxxxxx
Fixes: 4bcc595ccd80 ("printk: reinstate KERN_CONT for printing continuation lines")
Link: http://lkml.kernel.org/r/43b4e114724b2bdb0308fa86cb33aa07d3d67fad.1486510315.git.osandov@xxxxxx
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
kernel/stacktrace.c | 12 ++++--------
1 file changed, 4 insertions(+), 8 deletions(-)

--- a/kernel/stacktrace.c
+++ b/kernel/stacktrace.c
@@ -18,10 +18,8 @@ void print_stack_trace(struct stack_trac
if (WARN_ON(!trace->entries))
return;

- for (i = 0; i < trace->nr_entries; i++) {
- printk("%*c", 1 + spaces, ' ');
- print_ip_sym(trace->entries[i]);
- }
+ for (i = 0; i < trace->nr_entries; i++)
+ printk("%*c%pS\n", 1 + spaces, ' ', (void *)trace->entries[i]);
}
EXPORT_SYMBOL_GPL(print_stack_trace);

@@ -29,7 +27,6 @@ int snprint_stack_trace(char *buf, size_
struct stack_trace *trace, int spaces)
{
int i;
- unsigned long ip;
int generated;
int total = 0;

@@ -37,9 +34,8 @@ int snprint_stack_trace(char *buf, size_
return 0;

for (i = 0; i < trace->nr_entries; i++) {
- ip = trace->entries[i];
- generated = snprintf(buf, size, "%*c[<%p>] %pS\n",
- 1 + spaces, ' ', (void *) ip, (void *) ip);
+ generated = snprintf(buf, size, "%*c%pS\n", 1 + spaces, ' ',
+ (void *)trace->entries[i]);

total += generated;