The branch stable/12 has been updated by avg:
URL:
https://cgit.FreeBSD.org/src/commit/?id=2def2de60a6d0b979964bb67c5ff0e24d098e4a9
commit 2def2de60a6d0b979964bb67c5ff0e24d098e4a9
Author: Andriy Gapon <a...@freebsd.org>
AuthorDate: 2021-05-06 18:49:37 +0000
Commit: Andriy Gapon <a...@freebsd.org>
CommitDate: 2021-05-21 10:31:04 +0000
PCI hot-plug: use dedicated taskqueue for device attach / detach
Attaching and detaching devices can be heavy-weight and detaching can
sleep waiting for events. For that reason using the system-wide
single-threaded taskqueue_thread is not really appropriate.
There is even a possibility for a deadlock if taskqueue_thread is used
for detaching.
In fact, there is an easy to reproduce deadlock involving nvme, pass
and a sudden removal of an NVMe device.
A pass peripheral would not release a reference on an nvme sim until
pass_shutdown_kqueue() is executed via taskqueue_thread. But the
taskqueue's thread is blocked in nvme_detach() -> ... -> cam_sim_free()
because of the outstanding reference.
Sponsored by: CyberSecure
Reviewed by: mav, imp
(cherry picked from commit 12588ce02dd835b332952d9fece5881d943554a9)
---
sys/dev/pci/pci_pci.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)
diff --git a/sys/dev/pci/pci_pci.c b/sys/dev/pci/pci_pci.c
index ff3dcdc84c47..4b7560f499ef 100644
--- a/sys/dev/pci/pci_pci.c
+++ b/sys/dev/pci/pci_pci.c
@@ -922,6 +922,8 @@ SYSCTL_INT(_hw_pci, OID_AUTO, enable_pcie_hp, CTLFLAG_RDTUN,
&pci_enable_pcie_hp, 0,
"Enable support for native PCI-express HotPlug.");
+TASKQUEUE_DEFINE_THREAD(pci_hp);
+
static void
pcib_probe_hotplug(struct pcib_softc *sc)
{
@@ -1151,7 +1153,7 @@ pcib_pcie_hotplug_update(struct pcib_softc *sc, uint16_t
val, uint16_t mask,
*/
if (schedule_task &&
(pcib_hotplug_present(sc) != 0) != (sc->child != NULL))
- taskqueue_enqueue(taskqueue_thread, &sc->pcie_hp_task);
+ taskqueue_enqueue(taskqueue_pci_hp, &sc->pcie_hp_task);
}
static void
@@ -1443,7 +1445,7 @@ pcib_detach_hotplug(struct pcib_softc *sc)
error = pcib_release_pcie_irq(sc);
if (error)
return (error);
- taskqueue_drain(taskqueue_thread, &sc->pcie_hp_task);
+ taskqueue_drain(taskqueue_pci_hp, &sc->pcie_hp_task);
callout_drain(&sc->pcie_ab_timer);
callout_drain(&sc->pcie_cc_timer);
callout_drain(&sc->pcie_dll_timer);
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