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Subject[PATCH v2] stacktrace: fix address, newline ugliness
Date
From: Omar Sandoval <osandov@fb.com>

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
[ 5.195976] init_btrfs_fs+0x21/0x196 [btrfs]
[ 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

Fixes: 4bcc595ccd80 ("printk: reinstate KERN_CONT for printing continuation lines")
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Omar Sandoval <osandov@fb.com>
---
kernel/stacktrace.c | 12 ++++--------
1 file changed, 4 insertions(+), 8 deletions(-)

diff --git a/kernel/stacktrace.c b/kernel/stacktrace.c
index b6e4c16377c7..9c15a9124e83 100644
--- a/kernel/stacktrace.c
+++ b/kernel/stacktrace.c
@@ -18,10 +18,8 @@ void print_stack_trace(struct stack_trace *trace, int spaces)
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_t 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_t 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;

--
2.11.1
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