From: Sean Christopherson <seanjc@google.com>
To: Paolo Bonzini <pbonzini@redhat.com>,
Ingo Molnar <mingo@redhat.com>,
Peter Zijlstra <peterz@infradead.org>,
Juri Lelli <juri.lelli@redhat.com>,
Vincent Guittot <vincent.guittot@linaro.org>,
Marc Zyngier <maz@kernel.org>,
Oliver Upton <oliver.upton@linux.dev>,
Sean Christopherson <seanjc@google.com>,
Paul Walmsley <paul.walmsley@sifive.com>,
Palmer Dabbelt <palmer@dabbelt.com>,
Albert Ou <aou@eecs.berkeley.edu>
Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org,
linux-arm-kernel@lists.infradead.org, kvmarm@lists.linux.dev,
linux-riscv@lists.infradead.org,
David Matlack <dmatlack@google.com>,
Juergen Gross <jgross@suse.com>,
Stefano Stabellini <sstabellini@kernel.org>,
Oleksandr Tyshchenko <oleksandr_tyshchenko@epam.com>
Subject: [PATCH 08/12] sched/wait: Drop WQ_FLAG_EXCLUSIVE from add_wait_queue_priority()
Date: Tue, 1 Apr 2025 13:44:20 -0700 [thread overview]
Message-ID: <20250401204425.904001-9-seanjc@google.com> (raw)
In-Reply-To: <20250401204425.904001-1-seanjc@google.com>
Drop the setting of WQ_FLAG_EXCLUSIVE from add_wait_queue_priority() to
differentiate it from add_wait_queue_priority_exclusive(). The one and
only user add_wait_queue_priority(), Xen privcmd's irqfd_wakeup(),
unconditionally returns '0', i.e. doesn't actually operate in exclusive
mode.
Cc: Juergen Gross <jgross@suse.com>
Cc: Stefano Stabellini <sstabellini@kernel.org>
Cc: Oleksandr Tyshchenko <oleksandr_tyshchenko@epam.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
---
kernel/sched/wait.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/kernel/sched/wait.c b/kernel/sched/wait.c
index 80d90d1dc24d..2af0fc92e5d3 100644
--- a/kernel/sched/wait.c
+++ b/kernel/sched/wait.c
@@ -40,7 +40,7 @@ void add_wait_queue_priority(struct wait_queue_head *wq_head, struct wait_queue_
{
unsigned long flags;
- wq_entry->flags |= WQ_FLAG_EXCLUSIVE | WQ_FLAG_PRIORITY;
+ wq_entry->flags |= WQ_FLAG_PRIORITY;
spin_lock_irqsave(&wq_head->lock, flags);
__add_wait_queue(wq_head, wq_entry);
spin_unlock_irqrestore(&wq_head->lock, flags);
@@ -84,7 +84,7 @@ EXPORT_SYMBOL(remove_wait_queue);
* the non-exclusive tasks. Normally, exclusive tasks will be at the end of
* the list and any non-exclusive tasks will be woken first. A priority task
* may be at the head of the list, and can consume the event without any other
- * tasks being woken.
+ * tasks being woken if it's also an exclusive task.
*
* There are circumstances in which we can try to wake a task which has already
* started to run but is not in state TASK_RUNNING. try_to_wake_up() returns
--
2.49.0.504.g3bcea36a83-goog
next prev parent reply other threads:[~2025-04-01 20:47 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-04-01 20:44 [PATCH 00/12] KVM: Make irqfd registration globally unique Sean Christopherson
2025-04-01 20:44 ` [PATCH 01/12] KVM: Use a local struct to do the initial vfs_poll() on an irqfd Sean Christopherson
2025-04-01 20:44 ` [PATCH 02/12] KVM: Acquire SCRU lock outside of irqfds.lock during assignment Sean Christopherson
2025-04-01 20:44 ` [PATCH 03/12] KVM: Initialize irqfd waitqueue callback when adding to the queue Sean Christopherson
2025-04-01 20:44 ` [PATCH 04/12] KVM: Add irqfd to KVM's list via the vfs_poll() callback Sean Christopherson
2025-04-01 20:44 ` [PATCH 05/12] KVM: Add irqfd to eventfd's waitqueue while holding irqfds.lock Sean Christopherson
2025-04-01 20:44 ` [PATCH 06/12] sched/wait: Add a waitqueue helper for fully exclusive priority waiters Sean Christopherson
2025-04-02 18:40 ` K Prateek Nayak
2025-04-01 20:44 ` [PATCH 07/12] KVM: Disallow binding multiple irqfds to an eventfd with a priority waiter Sean Christopherson
2025-04-01 20:44 ` Sean Christopherson [this message]
2025-04-01 20:44 ` [PATCH 09/12] KVM: Drop sanity check that per-VM list of irqfds is unique Sean Christopherson
2025-04-01 20:44 ` [PATCH 10/12] KVM: selftests: Assert that eventfd() succeeds in Xen shinfo test Sean Christopherson
2025-04-01 20:44 ` [PATCH 11/12] KVM: selftests: Add utilities to create eventfds and do KVM_IRQFD Sean Christopherson
2025-04-01 20:44 ` [PATCH 12/12] KVM: selftests: Add a KVM_IRQFD test to verify uniqueness requirements Sean Christopherson
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