Author: bdrewery
Date: Wed Feb 14 18:43:50 2018
New Revision: 329271
URL: https://svnweb.freebsd.org/changeset/base/329271

Log:
  nanosleep(2): Fix bogus incrementing of rmtp by tc_tick_sbt on [EINTR].
  
  sbt is the time in the future that the tsleep_sbt() is expected to be 
completed
  at.  sbtt is the current time.  Depending on the precision with sysctl
  kern.timecounter.alloweddeviation the start time may be incremented by
  tc_tick_sbt.  The same increment is needed for the current time of sbtt before
  calculating the difference.  The impact of missing this increment is that rmtp
  may increase by one tc_tick_sbt on every early [EINTR] return.  If the same
  struct is passed in for rqtp as rmtp this can result in rqtp effectively
  incrementing by tc_tick_sbt and sleeping longer than originally intended.
  
  This problem was introduced in r247797.
  
  Reviewed by:  kib, markj, vangyzen (all on an older version of the test)
  MFC after:    2 weeks
  Sponsored by: Dell EMC
  Differential Revision:        https://reviews.freebsd.org/D14362

Modified:
  head/contrib/netbsd-tests/lib/libc/sys/t_nanosleep.c
  head/sys/kern/kern_time.c

Modified: head/contrib/netbsd-tests/lib/libc/sys/t_nanosleep.c
==============================================================================
--- head/contrib/netbsd-tests/lib/libc/sys/t_nanosleep.c        Wed Feb 14 
18:21:54 2018        (r329270)
+++ head/contrib/netbsd-tests/lib/libc/sys/t_nanosleep.c        Wed Feb 14 
18:43:50 2018        (r329271)
@@ -50,6 +50,15 @@ handler(int signo __unused)
        /* Nothing. */
 }
 
+static int got_info;
+static void
+info_handler(int signo __unused)
+{
+
+       got_info = 1;
+}
+
+
 ATF_TC(nanosleep_basic);
 ATF_TC_HEAD(nanosleep_basic, tc)
 {
@@ -176,12 +185,84 @@ ATF_TC_BODY(nanosleep_sig, tc)
                atf_tc_fail("signal did not interrupt nanosleep(2)");
 }
 
+ATF_TC(nanosleep_eintr);
+ATF_TC_HEAD(nanosleep_eintr, tc)
+{
+       atf_tc_set_md_var(tc, "descr", "Test [EINTR] for nanosleep(2)");
+       atf_tc_set_md_var(tc, "timeout", "7");
+}
+
+ATF_TC_BODY(nanosleep_eintr, tc)
+{
+       struct sigaction act;
+       struct timespec tso, ts;
+       pid_t pid;
+       int sta;
+
+       /*
+        * Test that [EINTR] properly handles rmtp for nanosleep(2).
+        */
+       pid = fork();
+
+       ATF_REQUIRE(pid >= 0);
+
+       got_info = 0;
+
+       if (pid == 0) {
+               act.sa_handler = info_handler;
+               sigemptyset(&act.sa_mask);
+               act.sa_flags = 0; /* Don't allow restart. */
+               ATF_REQUIRE(sigaction(SIGINFO, &act, NULL) == 0);
+
+               tso.tv_sec = 5;
+               tso.tv_nsec = 0;
+
+               ts.tv_sec = tso.tv_sec;
+               ts.tv_nsec = tso.tv_nsec;
+
+               errno = 0;
+               while (nanosleep(&ts, &ts) != 0) {
+                       ATF_REQUIRE_MSG(timespeccmp(&ts, &tso, <=),
+                           "errno=%d ts=%0.9f should be <= last tso=%0.9f\n",
+                           errno,
+                           ts.tv_sec + ts.tv_nsec / 1e9,
+                           tso.tv_sec + tso.tv_nsec / 1e9);
+                       if (errno == EINTR && got_info == 1) {
+                               got_info = 0;
+                               errno = 0;
+                               tso.tv_sec = ts.tv_sec;
+                               tso.tv_nsec = ts.tv_nsec;
+                               continue;
+                       }
+                       _exit(EXIT_FAILURE);
+               }
+
+               if (errno != 0)
+                       _exit(EXIT_FAILURE);
+
+               _exit(EXIT_SUCCESS);
+       }
+
+       /* Flood the process with SIGINFO until it exits. */
+       do {
+               for (int i = 0; i < 10; i++)
+                       ATF_REQUIRE(kill(pid, SIGINFO) == 0);
+               ATF_REQUIRE(usleep(10000) == 0);
+       } while (waitpid(pid, &sta, WNOHANG) == 0);
+
+       ATF_REQUIRE(WIFEXITED(sta) == 1);
+
+       if (WEXITSTATUS(sta) != EXIT_SUCCESS)
+               atf_tc_fail("nanosleep(2) handled rtmp incorrectly");
+}
+
 ATF_TP_ADD_TCS(tp)
 {
 
        ATF_TP_ADD_TC(tp, nanosleep_basic);
        ATF_TP_ADD_TC(tp, nanosleep_err);
        ATF_TP_ADD_TC(tp, nanosleep_sig);
+       ATF_TP_ADD_TC(tp, nanosleep_eintr);
 
        return atf_no_error();
 }

Modified: head/sys/kern/kern_time.c
==============================================================================
--- head/sys/kern/kern_time.c   Wed Feb 14 18:21:54 2018        (r329270)
+++ head/sys/kern/kern_time.c   Wed Feb 14 18:43:50 2018        (r329271)
@@ -563,7 +563,8 @@ kern_clock_nanosleep(struct thread *td, clockid_t cloc
        } while (error == 0 && is_abs_real && td->td_rtcgen == 0);
        td->td_rtcgen = 0;
        if (error != EWOULDBLOCK) {
-               TIMESEL(&sbtt, tmp);
+               if (TIMESEL(&sbtt, tmp))
+                       sbtt += tc_tick_sbt;
                if (sbtt >= sbt)
                        return (0);
                if (error == ERESTART)
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