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authorTejun Heo <tj@kernel.org>2024-10-02 10:33:37 -1000
committerTejun Heo <tj@kernel.org>2024-10-04 10:11:43 -1000
commitcc9877fb76771b7cbce6c9ec239f13a1d7759876 (patch)
treeb1354d02dc9414e978387d08b00c77a02d088355 /kernel/sched
parentfcbc423577ce28b5e470a2a47fed6724430cccdb (diff)
sched_ext: Improve error reporting during loading
When the BPF scheduler fails, ops.exit() allows rich error reporting through scx_exit_info. Use scx.exit() path consistently for all failures which can be caused by the BPF scheduler: - scx_ops_error() is called after ops.init() and ops.cgroup_init() failure to record error information. - ops.init_task() failure now uses scx_ops_error() instead of pr_err(). - The err_disable path updated to automatically trigger scx_ops_error() to cover cases that the error message hasn't already been generated and always return 0 indicating init success so that the error is reported through ops.exit(). Signed-off-by: Tejun Heo <tj@kernel.org> Cc: David Vernet <void@manifault.com> Cc: Daniel Hodges <hodges.daniel.scott@gmail.com> Cc: Changwoo Min <multics69@gmail.com> Cc: Andrea Righi <andrea.righi@linux.dev> Cc: Dan Schatzberg <schatzberg.dan@gmail.com>
Diffstat (limited to 'kernel/sched')
-rw-r--r--kernel/sched/ext.c30
1 files changed, 19 insertions, 11 deletions
diff --git a/kernel/sched/ext.c b/kernel/sched/ext.c
index 3cd7c50a51c5..76f04f3ace61 100644
--- a/kernel/sched/ext.c
+++ b/kernel/sched/ext.c
@@ -625,6 +625,10 @@ struct sched_ext_ops {
/**
* exit - Clean up after the BPF scheduler
* @info: Exit info
+ *
+ * ops.exit() is also called on ops.init() failure, which is a bit
+ * unusual. This is to allow rich reporting through @info on how
+ * ops.init() failed.
*/
void (*exit)(struct scx_exit_info *info);
@@ -4117,6 +4121,7 @@ static int scx_cgroup_init(void)
css->cgroup, &args);
if (ret) {
css_put(css);
+ scx_ops_error("ops.cgroup_init() failed (%d)", ret);
return ret;
}
tg->scx_flags |= SCX_TG_INITED;
@@ -5041,6 +5046,7 @@ static int scx_ops_enable(struct sched_ext_ops *ops, struct bpf_link *link)
if (ret) {
ret = ops_sanitize_err("init", ret);
cpus_read_unlock();
+ scx_ops_error("ops.init() failed (%d)", ret);
goto err_disable;
}
}
@@ -5150,8 +5156,8 @@ static int scx_ops_enable(struct sched_ext_ops *ops, struct bpf_link *link)
spin_lock_irq(&scx_tasks_lock);
scx_task_iter_exit(&sti);
spin_unlock_irq(&scx_tasks_lock);
- pr_err("sched_ext: ops.init_task() failed (%d) for %s[%d] while loading\n",
- ret, p->comm, p->pid);
+ scx_ops_error("ops.init_task() failed (%d) for %s[%d]",
+ ret, p->comm, p->pid);
goto err_disable_unlock_all;
}
@@ -5199,14 +5205,8 @@ static int scx_ops_enable(struct sched_ext_ops *ops, struct bpf_link *link)
scx_ops_bypass(false);
- /*
- * Returning an error code here would lose the recorded error
- * information. Exit indicating success so that the error is notified
- * through ops.exit() with all the details.
- */
if (!scx_ops_tryset_enable_state(SCX_OPS_ENABLED, SCX_OPS_ENABLING)) {
WARN_ON_ONCE(atomic_read(&scx_exit_kind) == SCX_EXIT_NONE);
- ret = 0;
goto err_disable;
}
@@ -5241,10 +5241,18 @@ err_disable_unlock_all:
scx_ops_bypass(false);
err_disable:
mutex_unlock(&scx_ops_enable_mutex);
- /* must be fully disabled before returning */
- scx_ops_disable(SCX_EXIT_ERROR);
+ /*
+ * Returning an error code here would not pass all the error information
+ * to userspace. Record errno using scx_ops_error() for cases
+ * scx_ops_error() wasn't already invoked and exit indicating success so
+ * that the error is notified through ops.exit() with all the details.
+ *
+ * Flush scx_ops_disable_work to ensure that error is reported before
+ * init completion.
+ */
+ scx_ops_error("scx_ops_enable() failed (%d)", ret);
kthread_flush_work(&scx_ops_disable_work);
- return ret;
+ return 0;
}