Re: bin/56422: zgrep -l sometimes hangs

[mlelstv%serpens.de@localhost (Michael van Elst)]

The following reply was made to PR bin/56422; it has been noted by GNATS.

From: mlelstv%serpens.de@localhost (Michael van Elst)
To: gnats-bugs%netbsd.org@localhost
Cc: 
Subject: Re: bin/56422: zgrep -l sometimes hangs
Date: Wed, 29 Sep 2021 20:25:42 -0000 (UTC)

 gson%gson.org@localhost (Andreas Gustafsson) writes:
 
 >  0  7920 1604 28360  79  0 24012   3732 wait    I    tty00 0:13.81 |   |-- -sh
 >  0 20716 7920     0   0  0 22232   1724 -       DE   tty00 0:00.00 |   | |-- (head)
 >  0 22105 7920 28360  79  0 24584   1768 pipe_wr I    tty00 0:00.00 |   | `-- gunzip
 
 
 head is exiting waiting for rpipe->pipe_draincv:
 
 fp ffffc000ba1d7b30 mi_switch() at ffffc0000057435c mi_switch+0x1fc
 fp ffffc000ba1d7b90 sleepq_block() at ffffc00000570cb8 sleepq_block+0xa8
 fp ffffc000ba1d7bd0 cv_wait_sig() at ffffc00000536e14 cv_wait_sig+0x44
 fp ffffc000ba1d7c00 pipeclose.part.0() at ffffc000005bcab0 pipeclose.part.0+0xac
 fp ffffc000ba1d7c30 pipe_close() at ffffc000005bccf8 pipe_close+0x18
 fp ffffc000ba1d7c40 closef() at ffffc0000053a554 closef+0x60
 fp ffffc000ba1d7c80 fd_free() at ffffc0000053cb68 fd_free+0x104
 fp ffffc000ba1d7d00 exit1() at ffffc00000548130 exit1+0xfc
 fp ffffc000ba1d7df0 sys_exit() at ffffc00000548a68 sys_exit+0x38
 fp ffffc000ba1d7e20 syscall() at ffffc000000adb14 syscall+0x194
 fp ffffc000ba1d7ed0 el0_trap() at ffffc000000b0ff0 el0_trap
 
 
 gunzip still waits writing to the pipe for wpipe->pipe_wcv.
 
 fp ffffc000ba85fc60 mi_switch() at ffffc0000057435c mi_switch+0x1fc
 fp ffffc000ba85fcc0 sleepq_block() at ffffc00000570cb8 sleepq_block+0xa8
 fp ffffc000ba85fd00 cv_wait_sig() at ffffc00000536e14 cv_wait_sig+0x44
 fp ffffc000ba85fd30 pipe_write() at ffffc000005bd224 pipe_write+0x1d4
 fp ffffc000ba85fda0 dofilewrite() at ffffc000005b7d60 dofilewrite+0x70
 fp ffffc000ba85fe20 syscall() at ffffc000000adb14 syscall+0x194
 fp ffffc000ba85fed0 el0_trap() at ffffc000000b0ff0 el0_trap
 
 
 killing gunzip with SIGPIPE releases the lock and gunzip and head
 exit. But unlike the first event after more than 8000 loops, the
 next hang happens after a few iterations.