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nptl: extend test coverage for sched_yield (RHEL-61561)

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Resolves: RHEL-61561
This commit is contained in:
Arjun Shankar 2025-03-14 15:48:58 +01:00
parent 91162ca365
commit efcdbdd0a0
2 changed files with 156 additions and 1 deletions
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151
glibc-RHEL-61561.patch Normal file
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@ -0,0 +1,151 @@
commit a9017caff3b77032d04e2e439f7c04a63241e63e
Author: Sergey Kolosov <skolosov@redhat.com>
Date: Tue Jan 28 23:56:26 2025 +0100
nptl: extend test coverage for sched_yield
We add sched_yield() API testing to the existing thread affinity
test case because it allows us to test sched_yield() operation
in the following scenarios:
* On a main thread.
* On multiple threads simultaneously.
* On every CPU the system reports simultaneously.
The ensures we exercise sched_yield() in as many scenarios as
we would exercise calls to the affinity functions.
Additionally, the test is improved by adding a semaphore to coordinate
all the threads running, so that an early starter thread won't consume
cpu resources that could be used to start the other threads.
Co-authored-by: DJ Delorie <dj@redhat.com>
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
diff --git a/sysdeps/unix/sysv/linux/tst-skeleton-affinity.c b/sysdeps/unix/sysv/linux/tst-skeleton-affinity.c
index afc8c1b96fa2f408..55ddcda2ce24e186 100644
--- a/sysdeps/unix/sysv/linux/tst-skeleton-affinity.c
+++ b/sysdeps/unix/sysv/linux/tst-skeleton-affinity.c
@@ -38,6 +38,7 @@
#include <sched.h>
#include <stdbool.h>
#include <stdio.h>
+#include <support/test-driver.h>
/* CPU set configuration determined. Can be used from early_test. */
struct conf
@@ -253,12 +254,12 @@ do_test (void)
if (getaffinity (sizeof (set), &set) < 0 && errno == ENOSYS)
{
puts ("warning: getaffinity not supported, test cannot run");
- return 0;
+ return EXIT_UNSUPPORTED;
}
if (sched_getcpu () < 0 && errno == ENOSYS)
{
puts ("warning: sched_getcpu not supported, test cannot run");
- return 0;
+ return EXIT_UNSUPPORTED;
}
}
diff --git a/sysdeps/unix/sysv/linux/tst-skeleton-thread-affinity.c b/sysdeps/unix/sysv/linux/tst-skeleton-thread-affinity.c
index 1445ea2d19430ce8..545a6c77c6fdd091 100644
--- a/sysdeps/unix/sysv/linux/tst-skeleton-thread-affinity.c
+++ b/sysdeps/unix/sysv/linux/tst-skeleton-thread-affinity.c
@@ -45,10 +45,14 @@ static int still_running;
/* 0 if no scheduling failures, 1 if failures are encountered. */
static int failed;
+/* Used to synchronize the threads. */
+static pthread_barrier_t barrier;
+
static void *
thread_burn_one_cpu (void *closure)
{
int cpu = (uintptr_t) closure;
+ xpthread_barrier_wait (&barrier);
while (__atomic_load_n (&still_running, __ATOMIC_RELAXED) == 0)
{
int current = sched_getcpu ();
@@ -61,6 +65,11 @@ thread_burn_one_cpu (void *closure)
__atomic_store_n (&still_running, 1, __ATOMIC_RELAXED);
}
}
+ if (sched_yield () != 0)
+ {
+ printf ("error: sched_yield() failed for cpu %d\n", cpu);
+ __atomic_store_n (&failed, 1, __ATOMIC_RELAXED);
+ }
return NULL;
}
@@ -78,6 +87,7 @@ thread_burn_any_cpu (void *closure)
{
struct burn_thread *param = closure;
+ xpthread_barrier_wait (&barrier);
/* Schedule this thread around a bit to see if it lands on another
CPU. Run this for 2 seconds, once with sched_yield, once
without. */
@@ -99,7 +109,11 @@ thread_burn_any_cpu (void *closure)
CPU_SET_S (cpu, CPU_ALLOC_SIZE (param->conf->set_size),
param->seen_set);
if (pass == 1)
- sched_yield ();
+ if (sched_yield () != 0)
+ {
+ printf ("error: sched_yield() failed for cpu %d\n", cpu);
+ __atomic_store_n (&failed, 1, __ATOMIC_RELAXED);
+ }
}
}
return NULL;
@@ -156,6 +170,7 @@ early_test (struct conf *conf)
= calloc (conf->last_cpu + 1, sizeof (*other_threads));
cpu_set_t *initial_set = CPU_ALLOC (conf->set_size);
cpu_set_t *scratch_set = CPU_ALLOC (conf->set_size);
+ int num_available_cpus = 0;
if (pinned_threads == NULL || other_threads == NULL
|| initial_set == NULL || scratch_set == NULL)
@@ -172,6 +187,7 @@ early_test (struct conf *conf)
{
if (!CPU_ISSET_S (cpu, CPU_ALLOC_SIZE (conf->set_size), initial_set))
continue;
+ num_available_cpus ++;
other_threads[cpu].conf = conf;
other_threads[cpu].initial_set = initial_set;
other_threads[cpu].thread = cpu;
@@ -194,6 +210,15 @@ early_test (struct conf *conf)
}
support_set_small_thread_stack_size (&attr);
+ /* This count assumes that all the threads below are created
+ successfully, and call pthread_barrier_wait(). If any threads
+ fail to be created, this function will return FALSE (failure) and
+ the waiting threads will eventually time out the whole test.
+ This is acceptable because we're not testing thread creation and
+ assume all threads will be created, and failure here implies a
+ failure outside the test's scope. */
+ xpthread_barrier_init (&barrier, NULL, num_available_cpus * 2 + 1);
+
/* Spawn a thread pinned to each available CPU. */
for (int cpu = 0; cpu <= conf->last_cpu; ++cpu)
{
@@ -245,6 +270,15 @@ early_test (struct conf *conf)
}
}
+ /* Test that sched_yield() works correctly in the main thread. This
+ also gives the kernel an opportunity to run the other threads,
+ randomizing thread startup a bit. */
+ if (sched_yield () != 0)
+ {
+ printf ("error: sched_yield() failed for main thread\n");
+ __atomic_store_n (&failed, 1, __ATOMIC_RELAXED);
+ }
+
/* Main thread. */
struct burn_thread main_thread;
main_thread.conf = conf;

6
glibc.spec
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@ -157,7 +157,7 @@ end \
Summary: The GNU libc libraries
Name: glibc
Version: %{glibcversion}
Release: 177%{?dist}
Release: 178%{?dist}
# In general, GPLv2+ is used by programs, LGPLv2+ is used for
# libraries.
@ -1149,6 +1149,7 @@ Patch841: glibc-RHEL-56627-6.patch
Patch842: glibc-RHEL-56627-7.patch
Patch843: glibc-RHEL-56627-8.patch
Patch844: glibc-RHEL-28119.patch
Patch845: glibc-RHEL-61561.patch
##############################################################################
# Continued list of core "glibc" package information:
@ -3142,6 +3143,9 @@ update_gconv_modules_cache ()
%endif
%changelog
* Fri Mar 14 2025 Arjun Shankar <arjun@redhat.com> - 2.34-178
- nptl: extend test coverage for sched_yield (RHEL-61561)
* Fri Mar 14 2025 Arjun Shankar <arjun@redhat.com> - 2.34-177
- Fix missing rseq acceleration for sched_getcpu (RHEL-28119)