Messages in this thread | | | Date | Wed, 27 Apr 2011 14:57:10 +0200 | From | Oleg Nesterov <> | Subject | Re: [PATCH v2 5/6] signal: sys_sigprocmask() needs retarget_shared_pending() |
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On 04/26, Linus Torvalds wrote: > > > + sigemptyset(&new_full_set); > > + if (how == SIG_SETMASK) > > + new_full_set = current->blocked; > > + new_full_set.sig[0] = new_set; > > Ugh. This is just ugly.
Agreed.
> Could we not instead turn the whole thing into a "clear these bits" > and "set these bits", and get rid of the "how" entirely for the helper > function? > > IOW, we'd have > > switch (how) { > case SIG_BLOCK: > clear_bits = 0; > set_bits = new_set; > break; > case SIG_UNBLOCK: > clear_bits = new_set; > set_bits = 0; > break > case SIG_SET: > clear_bits = low_bits; > set_bits = new_set; > break; > default: > return -EINVAL; > } > > and notice how you now can do that helper function *WITHOUT* any > conditionals, and just make it do > > sigprocmask(&clear, &set, NULL); > > which handles all cases correctly (just "andn clear" + "or set") with > no if's or switch'es. > > This is why I _detest_ that idiotic "sigprocmask()" interface.
Agreed, but...
Yes, sigprocmask(how) is ugly, but there are sys_rt_sigprocmask() and sys_sigprocmask() which have to handle these SIG_* operations anyway. So, I think we should do:
1. Almost all callers of sigprocmask() use SIG_SETMASK, we can simply change them to use set_current_blocked().
2. Add the new helper (probably like you suggested) and convert other 9 callers.
3. Unexport sigprocmask() and remove the last "*oldset" argument, it should be only used by sys_*sigprocmask() syscalls.
But firstly I'd like to finish this "don't change ->blocked directly" conversion. And this patch changes sys_sigprocmask() so that it looks similar to sys_rt_sigprocmask().
What do you think?
If you can't accept sys_sigprocmask()->sigprocmask(), will you agree with
SYSCALL_DEFINE3(sigprocmask, int, how, old_sigset_t __user *, nset, old_sigset_t __user *, oset) { old_sigset_t old_set, new_set; sigset_t new_blocked;
old_set = current->blocked.sig[0];
if (nset) { if (copy_from_user(&new_set, nset, sizeof(*nset))) return -EFAULT; new_set &= ~(sigmask(SIGKILL) | sigmask(SIGSTOP));
new_blocked = current->blocked;
switch (how) { case SIG_BLOCK: sigaddsetmask(&new_blocked, new_set); break; case SIG_UNBLOCK: sigdelsetmask(&new_blocked, new_set); break; case SIG_SETMASK: new_blocked.sig[0] = new_set; break; default: return -EINVAL; }
set_current_blocked(&new_blocked); }
if (oset) { if (copy_to_user(oset, &old_set, sizeof(*oset))) return -EFAULT; }
return 0; } ?
Oleg.
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