On 06/12/12 22:09, Al Viro wrote: > On Thu, Dec 06, 2012 at 11:17:34AM +0000, James Hogan wrote: > >> Agreed, it looks wrong. Looking at the sh version, is there a particular >> reason to only check for -EFAULT and not the other errors that >> do_sigaltstack can return (-EPERM, -EINVAL, and -ENOMEM)? > > See commit fae2ae2a900a5c7bb385fe4075f343e7e2d5daa2 Thanks :) > >>> BTW, what's to stop the syscall restart triggering if you catch a signal >>> while in rt_sigreturn(2)? >> >> I'm not sure I understand how that could cause a problem. Could you >> elaborate the sequence of events? >> >> The signal restart is triggered by the return value register, so >> rt_sigreturn would have to return -ERESTART*. This could happen if the >> signal handler overwrote the return value in the sigcontext (which as >> far as I can tell could also happen on ARM), or if the syscall that was >> originally interrupted by the signal has -ERESTARTNOINTR || >> (-ERESTARTSYS && SA_RESTART), but in that case rt_sigreturn has already >> switched back to the context of the original syscall so that's the right >> thing to do isn't it? I've probably missed something important :-) > > [we probably need something along the lines of braindump below in > somewhere in Documentation/*; comments and improvements are very > welcome - this is just a starting point. We *do* need some coherent > explanation of signal semantics, judging by how often people step on > the same landmines...] Thanks, this helps a lot. Cheers James -- To unsubscribe from this list: send the line "unsubscribe linux-arch" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
