[Crash-utility] Re: [PATCH] Fix for log command printed a couple of empty lines
Hi Lianbo,
Thank you for fixing it quickly.
btw, seeing 99bb57ac98af, I had a couple of questions, is there a way to
print the original (not mangled) log buffer?
also, if the log buffer has lines like "_R ... +" which are not rust
symbols unexpectedly, how are they printed?
(nice function, but maybe such function should be an option imho..)
Thanks,
Kazu
On 2025/09/17 7:55, Tao Liu wrote:
> applied:
https://github.com/crash-utility/crash/commit/0df76345db8f7bb2ce70138eee6...
>
> On Wed, Sep 17, 2025 at 10:34 AM Tao Liu <ltao(a)redhat.com> wrote:
>>
>> Hi Lianbo,
>>
>> Thanks for the fix, LGTM, ack.
>>
>> Thanks,
>> Tao Liu
>>
>> On Tue, Sep 16, 2025 at 8:05 PM Lianbo Jiang <lijiang(a)redhat.com> wrote:
>>>
>>> The log command printed a couple of empty lines (only timestamps), which
>>> was caused by the commit 99bb57ac98af ("Enable resolving mangled Rust
>>> symbol in lockless ring buffer"), E.g:
>>>
>>> $ diff -u log.pre log.cur
>>> --- log.pre 2025-09-16 13:14:31.022206514 +0900
>>> +++ log.cur 2025-09-16 13:14:56.220390987 +0900
>>> @@ -210,7 +210,7 @@
>>> [ 0.169375] clocksource: jiffies: mask: 0xffffffff max_cycles:
0xffffffff, max_idle_ns: 1911260446275000 ns
>>> [ 0.169375] futex hash table entries: 1024 (order: 4, 65536 bytes,
linear)
>>> [ 0.169375] pinctrl core: initialized pinctrl subsystem
>>> -[ 0.172925] NET: Registered PF_NETLINK/PF_ROUTE protocol family
>>> +[ 0.172925]
>>> [ 0.172983] DMA: preallocated 512 KiB GFP_KERNEL pool for atomic
allocations
>>> [ 0.172986] DMA: preallocated 512 KiB GFP_KERNEL|GFP_DMA pool for
atomic allocations
>>> [ 0.172988] DMA: preallocated 512 KiB GFP_KERNEL|GFP_DMA32 pool for
atomic allocations
>>> @@ -807,7 +807,7 @@
>>> [771438.513231] entry_SYSCALL_64_after_hwframe+0x72/0xdc
>>> [771438.513423] RIP: 0033:0x7fbd9f8fda57
>>> [771438.513576] Code: 0f 00 f7 d8 64 89 02 48 c7 c0 ff ff ff ff eb b7 0f
1f 00 f3 0f 1e fa 64 8b 04 25 18 00 00 00 85 c0 75 10 b8 01 00 00 00 0f 05 <48> 3d
00 f0 ff ff 77 51 c3 48 83 ec 28 48 89 54 24 18 48 89 74 24
>>> -[771438.514251] RSP: 002b:00007ffee0de2b98 EFLAGS: 00000246 ORIG_RAX:
0000000000000001
>>> +[771438.514251]
>>> [771438.514534] RAX: ffffffffffffffda RBX: 0000000000000002 RCX:
00007fbd9f8fda57
>>> [771438.514800] RDX: 0000000000000002 RSI: 00005647ccc0a330 RDI:
0000000000000001
>>> [771438.515066] RBP: 00005647ccc0a330 R08: 0000000000000003 R09:
0000000000000000
>>>
>>> This is because the strchrnul() returns a pointer to the null byte
>>> instead NULL if the char to be searched is not in the string. Given
>>> that, let's replace the strchrnul() with the strrchr().
>>>
>>> Fixes: 99bb57ac98af ("Enable resolving mangled Rust symbol in lockless
ring buffer")
>>> Reported-by: Kazuhito Hagio <k-hagio-ab(a)nec.com>
>>> Signed-off-by: Lianbo Jiang <lijiang(a)redhat.com>
>>> ---
>>> printk.c | 2 +-
>>> 1 file changed, 1 insertion(+), 1 deletion(-)
>>>
>>> diff --git a/printk.c b/printk.c
>>> index ae28c4fa0b21..51b618e2a434 100644
>>> --- a/printk.c
>>> +++ b/printk.c
>>> @@ -221,7 +221,7 @@ dump_record(struct prb_map *m, unsigned long id, int
msg_flags)
>>> char *p1 = strstr(buf, "_R");
>>> if (!p1)
>>> p1 = strstr(buf, "_ZN");
>>> - char *p2 = strchrnul(buf, '+');
>>> + char *p2 = strrchr(buf, '+');
>>> if (p1 && p2) {
>>> char mangled[BUFSIZE] = {0};
>>> char demangled[BUFSIZE] = {0};
>>> --
>>> 2.50.1
>>>