On 02/27, Will Drewry wrote: > > On Mon, Feb 27, 2012 at 11:22 AM, Oleg Nesterov <oleg@xxxxxxxxxx> wrote: > > On 02/24, Will Drewry wrote: > >> > >> To ensure that SIGSYS delivery occurs on return from the triggering > >> system call, SIGSYS is added to the SYNCHRONOUS_MASK macro. > > > > Hmm. Can't understand... please help. > > > >> #define SYNCHRONOUS_MASK \ > >> (sigmask(SIGSEGV) | sigmask(SIGBUS) | sigmask(SIGILL) | \ > >> - sigmask(SIGTRAP) | sigmask(SIGFPE)) > >> + sigmask(SIGTRAP) | sigmask(SIGFPE) | sigmask(SIGSYS)) > > > > Why? > > > > SYNCHRONOUS_MASK just tells dequeue_signal() "pick them first". > > This is needed to make sure that the handler for, say SIGSEGV, > > can use ucontext->ip as a faulting addr. > > I think that Roland covered this. (Since the syscall_rollback was > called it's nice to let our handler get first go.) OK, except I do not really understand the "our handler get first go". Suppose SIGSYS "races" with the pending SIGHUP. With this change the caller for SIGHUP will be called first. But yes, setup_frame() will be called for SIGSYS first. Hopefully this is what you want. > > But seccomp adds info->si_call_addr, this looks unneeded. > > True enough. I can drop it. Hmm. I meant, the change in SYNCHRONOUS_MASK looks unneeded. Please keep ->si_call_addr, it is much more convenient than ucontext_t in userspace. > It'd only be useful if the SIGSYS wasn't > being forced and the signal was being handled without ucontext_t > access. No, force_ doesn't make any difference in this sense... In short, the patch looks fine to me, but if you resend it may be you can update the changelog. Oleg. -- To unsubscribe from this list: send the line "unsubscribe linux-doc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
