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    SubjectRe: [RFC PATCH 1/5] signal: Teach sigsuspend to use set_user_sigmask
    David Laight <David.Laight@ACULAB.COM> writes:

    > From: David Laight
    >> Sent: 11 June 2019 10:52
    > ...
    >> If I have an application that has a loop with a pselect call that
    >> enables SIGINT (without a handler) and, for whatever reason,
    >> one of the fd is always 'ready' then I'd expect a SIGINT
    >> (from ^C) to terminate the program.
    >>
    >> A quick test program:
    >>
    >> #include <sys/time.h>
    >> #include <sys/types.h>
    >> #include <unistd.h>
    >>
    >> #include <sys/select.h>
    >> #include <signal.h>
    >>
    >> int main(int argc, char **argv)
    >> {
    >> fd_set readfds;
    >> sigset_t sig_int;
    >> struct timespec delay = {1, 0};
    >>
    >> sigfillset(&sig_int);
    >> sigdelset(&sig_int, SIGINT);
    >>
    >> sighold(SIGINT);
    >>
    >> for (;;) {
    >> FD_ZERO(&readfds);
    >> FD_SET(0, &readfds);
    >> pselect(1, &readfds, NULL, NULL, &delay, &sig_int);
    >>
    >> poll(0,0,1000);
    >> }
    >> }
    >>
    >> Run under strace to see what is happening and send SIGINT from a different terminal.
    >> The program sleeps for a second in each of the pselect() and poll() calls.
    >> Send a SIGINT and in terminates after pselect() returns ERESTARTNOHAND.
    >>
    >> Run again, this time press enter - making fd 0 readable.
    >> pselect() returns 1, but the program still exits.
    >> (Tested on a 5.1.0-rc5 kernel.)
    >>
    >> If a signal handler were defined it should be called instead.
    >
    > If I add a signal handler for SIGINT it is called when pselect()
    > returns regardless of the return value.

    That is odd. Is this with Oleg's fix applied?

    Eric

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