Messages in this thread | | | Date | Thu, 25 Nov 2004 06:09:53 -0200 | From | Marcelo Tosatti <> | Subject | Re: nanosleep interrupted by ignored signals |
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On Wed, Nov 24, 2004 at 07:06:27PM -0800, Matt Mackall wrote: > On Wed, Nov 24, 2004 at 06:45:05PM -0800, George Anzinger wrote: > > Matt Mackall wrote: > > >Take the following trivial program: > > > > > >#include <unistd.h> > > > > > >int main(void) > > >{ > > > sleep(10); > > > return 0; > > >} > > > > > >Run it in an xterm. Note that resizing the xterm has no effect on the > > >process. Now do the same with strace: > > > > > >brk(0x80495bc) = 0x80495bc > > >brk(0x804a000) = 0x804a000 > > >rt_sigprocmask(SIG_BLOCK, [CHLD], [], 8) = 0 > > >rt_sigaction(SIGCHLD, NULL, {SIG_DFL}, 8) = 0 > > >rt_sigprocmask(SIG_SETMASK, [], NULL, 8) = 0 > > >nanosleep({10, 0}, 0xbffff548) = -1 EINTR (Interrupted system > > >call) > > >--- SIGWINCH (Window changed) --- > > >_exit(0) = ? > > > > > >In short, nanosleep is getting interrupted by signals that are > > >supposedly ignored when a process is being praced. This appears to be > > >a long-standing bug. > > > > > >It also appears to be a long-known bug. I found some old discussion of this > > >problem here but no sign of any resolution: > > > > > >http://www.ussg.iu.edu/hypermail/linux/kernel/0108.1/1448.html > > > > > >What's the current thinking on this? > > > > This should have been resolved with the 2.6 changes, in particular, the > > restart code. What kernel are you using? > > Indeed it is. Forgot I still had 2.4 on the box in question, didn't > notice the restart bit when comparing the 2.6 code against the thread > above. Mea culpa.
George,
Is it worth/necessary to fix this bug in v2.4 ?
Quoting yourself
"This is an issue for debugging also (same ptrace...). The fix is to fix nano_sleep to match the standard which says it should only return on a signal if the signal is delivered to the program (i.e. not on internal "do nothing" signals). Signal in the kernel returns 1 if it calls the task and 0 otherwise, thus nano sleep might be changed as follows: "
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