diff options
| author | Jia Jia <physicalmtea@gmail.com> | 2026-09-19 16:39:33 +0800 |
|---|---|---|
| committer | Michael S. Tsirkin <mst@redhat.com> | 2026-11-02 09:07:01 -0500 |
| commit | cf0a5805d43236e308f14188f9737ddcf83fb53a (patch) | |
| tree | 0c677441b7e8d3c70ec16ae43f97b6f7571855ff | |
| parent | 434d2bc41bd0c0ac576d4d259bd9f2ab49071174 (diff) | |
vduse: avoid infinite loop when no affinity CPU is online
If all CPUs in vq->irq_affinity are offline, cpumask_next() walks to the
end of the mask, and the loop then resets the cursor to IRQ_UNBOUND and
restarts the scan. When VDUSE_VQ_INJECT_IRQ is issued, the intersection of
vq->irq_affinity and cpu_online_mask is empty, so the caller busy-loops in
kernel context on its current CPU (e.g. CPU2).
Replace the while loop in vduse_vq_update_effective_cpu() with
cpumask_next_and_wrap() to find the intersection of vq->irq_affinity and
cpu_online_mask in a single wrapped scan. If the intersection is empty, set
curr_cpu to IRQ_UNBOUND and let the existing unbound workqueue handle
injection, avoiding repeated rescans when all CPUs in the affinity are
offline. Use cpus_read_lock()/cpus_read_unlock() to keep the selected CPU
online.
Fixes: 28f6288eb63d ("vduse: Support set_vq_affinity callback")
Signed-off-by: Jia Jia <physicalmtea@gmail.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Message-ID: <20260919083933.104437-1-physicalmtea@gmail.com>
| -rw-r--r-- | drivers/vdpa/vdpa_user/vduse_dev.c | 15 |
1 files changed, 7 insertions, 8 deletions
diff --git a/drivers/vdpa/vdpa_user/vduse_dev.c b/drivers/vdpa/vdpa_user/vduse_dev.c index 49a231bdf948..f953353b50b4 100644 --- a/drivers/vdpa/vdpa_user/vduse_dev.c +++ b/drivers/vdpa/vdpa_user/vduse_dev.c @@ -15,6 +15,7 @@ #include <linux/module.h> #include <linux/cdev.h> #include <linux/device.h> +#include <linux/cpu.h> #include <linux/eventfd.h> #include <linux/slab.h> #include <linux/wait.h> @@ -1430,14 +1431,10 @@ static void vduse_vq_update_effective_cpu(struct vduse_virtqueue *vq) { int curr_cpu = vq->irq_effective_cpu; - while (true) { - curr_cpu = cpumask_next(curr_cpu, &vq->irq_affinity); - if (cpu_online(curr_cpu)) - break; - - if (curr_cpu >= nr_cpu_ids) - curr_cpu = IRQ_UNBOUND; - } + curr_cpu = cpumask_next_and_wrap(curr_cpu, &vq->irq_affinity, + cpu_online_mask); + if (curr_cpu >= nr_cpu_ids) + curr_cpu = IRQ_UNBOUND; vq->irq_effective_cpu = curr_cpu; } @@ -1672,10 +1669,12 @@ static long vduse_dev_ioctl(struct file *file, unsigned int cmd, ret = 0; index = array_index_nospec(index, dev->vq_num); if (!vduse_vq_signal_irqfd(dev->vqs[index])) { + cpus_read_lock(); vduse_vq_update_effective_cpu(dev->vqs[index]); ret = vduse_dev_queue_irq_work(dev, &dev->vqs[index]->inject, dev->vqs[index]->irq_effective_cpu); + cpus_read_unlock(); } break; } |