Fixed
Created: Apr 27, 2014
Updated: Dec 3, 2018
Resolved Date: May 18, 2014
Previous ID: LIN5-18613
Found In Version: 6.0
Fix Version: 6.0.0.7
Severity: Standard
Applicable for: Wind River Linux 6
Component/s: Kernel
With the same application, but it do different behavior in WRLinux 5.0 RCPL3 and RCPL12
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Differences:
RCPL3:
root@ localhost:~# ps -auf
USER PID %CPU %MEM VSZ RSS TTY STAT START TIME COMMAND
root 8510 0.0 0.0 3448 1700 pts/1 Ss 16:10 0:00 -sh
root 8507 1.1 0.1 25648 5080 pts/1 Sl+ 16:12 0:00 \_ /local/bin/imish
RCPL12:
root@ PC2:~# ps -auf
USER PID %CPU %MEM VSZ RSS TTY STAT START TIME COMMAND
root 16863 0.0 0.0 3448 1700 pts/1 Ss 16:20 0:00 -sh
root 16828 1.1 0.1 25648 5080 pts/1 Sl+ 16:32 0:00 \_ /local/bin/imish
After Kill -9 8510 and 16863 ,
RCPL3:
root@ localhost:~# ps -ef | grep imish
root 16874 16831 0 16:40 pts/2 00:00:00 grep imish
RCPL12:
root@PC2:~# ps -ef | grep imish
root 16828 16863 0 16:32 pts/1 00:00:00 /local/bin/imish
root 16874 16831 0 16:40 pts/2 00:00:00 grep imish
imish got in to wrong status and not exited in RCPL12 version; but RCPL3’ process has exited normally.
The attachment is the strace from killing parant process to the end.
From the strace we can see in RCL12, there is a more line SIGCONT signal than RCPL3, is it the root cause?
Note: In customer’s process “imish”, they set
SIGHUP ? action: SIGIGN;
SIGINT ? action: user defined.;
SIGTERM ? action: calling exit;
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After investigation, this issue looks only have relation with kernel(update glibc will not trigger this issue).
The error occur in read function when application receiving SIGHUP(should ignore it), in application, "read(0,buf,1)" returns 0 in RPCL3 but return -1 in RPCL12.
The different return value causes the final different process state.
RCPL3
/***********************************/
rt_sigaction(SIGHUP, {SIG_IGN, [HUP], SA_RESTART}, {0x805f4c0, [HUP], SA_RESTART}, 8) = 0 rt_sigprocmask(SIG_SETMASK, [HUP], NULL, 8) = 0
kill(0, SIGHUP) = 0
sigreturn() (mask []) = 3
--- SIGHUP {si_signo=SIGHUP, si_code=SI_USER, si_pid=8507, si_uid=0} ---
read(0, "", 1) = 0
time(NULL) = 1397232281
rt_sigprocmask(SIG_BLOCK, [HUP INT QUIT TERM CONT STOP TS /***********************************/
RCPL12
/***********************************/
rt_sigprocmask(SIG_BLOCK, [CONT], [HUP CONT], 8) = 0 rt_sigaction(SIGCONT, {SIG_DFL, [CONT], SA_RESTART}, {0x805f680, [CONT], SA_RESTART}, 8) = 0 rt_sigprocmask(SIG_SETMASK, [HUP CONT], NULL, 8) = 0
kill(0, SIGCONT) = 0
sigreturn() (mask [HUP]) = 1
--- SIGCONT {si_signo=SIGCONT, si_code=SI_USER, si_pid=16828, si_uid=0} --- rt_sigprocmask(SIG_BLOCK, [HUP], [HUP], 8) = 0 ioctl(0, SNDCTL_TMR_STOP or SNDRV_TIMER_IOCTL_GINFO or TCSETSW, {B38400 opost isig icanon echo ...}) = 0 rt_sigaction(SIGHUP, {SIG_IGN, [HUP], SA_RESTART}, {0x805f680, [HUP], SA_RESTART}, 8) = 0 rt_sigprocmask(SIG_SETMASK, [HUP], NULL, 8) = 0
kill(0, SIGHUP) = 0
sigreturn() (mask []) = 3
--- SIGHUP {si_signo=SIGHUP, si_code=SI_USER, si_pid=16828, si_uid=0} ---
read(0, 0xbfc8eb6f, 1) = -1 EIO (Input/output error)
write(1, "\7", 1) = -1 EIO (Input/output error)
ioctl(0, FIONREAD, [0]) = 0
ioctl(0, SNDCTL_TMR_TIMEBASE or SNDRV_TIMER_IOCTL_NEXT_DEVICE or TCGETS, {B38400 opost isig icanon echo ...}) = 0 ioctl(0, SNDCTL_TMR_STOP or SNDRV_TIMER_IOCTL_GINFO or TCSETSW, {B38400 opost isig -icanon -echo ...}) = 0
read(0, 0xbfc8eb6f, 1) = -1 EIO (Input/output error)
/***********************************/
Produce Steps:
1. Use ssh to login on a target.
2. Run example process.
3. on target, run `strace -p xx`
4. On another ssh sesssion, Kill -9 the parent process to see what happened to child process in strace log of target
I've put the example codes into attachment.
