* Arnd Bergmann: > On Thu, Nov 15, 2018 at 7:30 AM Dmitry V. Levin <ldv@xxxxxxxxxxxx> wrote: >> On Thu, Nov 15, 2018 at 06:39:03AM -0800, Arnd Bergmann wrote: >> > On Thu, Nov 15, 2018 at 6:05 AM Dmitry V. Levin wrote: >> > > On Thu, Apr 20, 2017 at 03:20:51PM +0200, Albert ARIBAUD wrote: >> >> 1. strace needs a race-free invocation of wait4(2) or waitid(2) >> with a different signal mask, this cannot be achieved without >> an extended version of syscall, similar to pselect6(2) extension >> over select(2) and ppoll(2) extension over poll(2). >> >> Signal mask specification in linux requires two parameters: >> "const sigset_t *sigmask" and "size_t sigsetsize". >> Creating pwait6(2) as an extension of wait4(2) with two arguments >> is straightforward. >> Creating pwaitid(2) as an extension of waitid(2) that already has 5 >> arguments would require an indirection similar to pselect6(2). > > Getting back to this point: you could also do the same thing with > the CLONE_FD approach from Josh Triplett[1] or Casey Dahlin's > older waitfd() syscall, correct? A descriptor-based solution would not be useful to glibc because applications assume that glibc does not (persistently) open any file descriptors behind t heir back. Thanks, Florian
