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&gt; wrote:

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&gt; 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&gt; 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&gt; >>> Signed-off-by: Lianbo Jiang <lijiang(a)redhat.com&gt; >>> --- >>> 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 >>>

On 2025/09/17 16:20, lijiang wrote: Thank you for considering, these look good to me. also, if text_len is limited to BUFSIZE for this function, maybe it should be only when "log -R" ? It's just confusing that we see different logs in crash "log" and vmcore-dmesg.txt etc, and like this time, if there is a bug in the demangling process, then we would like to check the original messages. Thanks, Kazu > > Thanks > Lianbo > > (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... <https://github.com/crash-utility/crash/commit/0df76345db8f7bb2ce70138eee6... > > > > On Wed, Sep 17, 2025 at 10:34 AM Tao Liu <ltao(a)redhat.com > <mailto:ltao@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 > <mailto:lijiang@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 > <mailto:k-hagio-ab@nec.com>> > >>> Signed-off-by: Lianbo Jiang <lijiang(a)redhat.com > <mailto:lijiang@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 > >>> >