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nanosleep(2): Fix bogus incrementing of rmtp by tc_tick_sbt on [EINTR].

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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
This commit is contained in:
Bryan Drewery 2018-02-14 18:43:50 +00:00
parent f52add1296
commit 70c144dc78
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=329271
2 changed files with 83 additions and 1 deletions
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81
contrib/netbsd-tests/lib/libc/sys/t_nanosleep.c
View File

@ -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();
}

3
sys/kern/kern_time.c
View File

@ -563,7 +563,8 @@ kern_clock_nanosleep(struct thread *td, clockid_t clock_id, int flags,
} 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)