tipc: avoid busy looping in tipc_exit_net()
Blamed commit introduced a busy-wait loop in tipc_exit_net()
to wait for pending UDP bearer cleanup works to complete:
while (atomic_read(&tn->wq_count))
cond_resched();
This loop can busy-wait for a long time if cond_resched() is a NOP. This
typically happens if the netns exit is executed by a high priority task,
or under kernels configured without preemption (CONFIG_PREEMPT_NONE). In
such cases, it wastes CPU cycles and can lead to soft lockups.
Fix this by replacing the busy loop with wait_var_event(), allowing the
thread to sleep properly until the work queue count reaches zero.
Accordingly, update cleanup_bearer() to use atomic_dec_and_test() and
wake_up_var() to wake up the waiter when the count drops to zero.
This uses the global wait queue hash table, avoiding the need to bloat
struct tipc_net with a wait_queue_head_t. The atomic_dec_and_test()
provides the necessary memory barrier to ensure the wakeup is not missed.
Analysis
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Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).
| Vendor | Product | Default status | Versions | |||||||||||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Linux | Linux | unaffected |
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| Linux | Linux | affected |
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No data.
No data.
No data available yet.
No vendor fix or workaround currently provided.
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Fri, 04 Sep 2026 17:00:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| Description | In the Linux kernel, the following vulnerability has been resolved: tipc: avoid busy looping in tipc_exit_net() Blamed commit introduced a busy-wait loop in tipc_exit_net() to wait for pending UDP bearer cleanup works to complete: while (atomic_read(&tn->wq_count)) cond_resched(); This loop can busy-wait for a long time if cond_resched() is a NOP. This typically happens if the netns exit is executed by a high priority task, or under kernels configured without preemption (CONFIG_PREEMPT_NONE). In such cases, it wastes CPU cycles and can lead to soft lockups. Fix this by replacing the busy loop with wait_var_event(), allowing the thread to sleep properly until the work queue count reaches zero. Accordingly, update cleanup_bearer() to use atomic_dec_and_test() and wake_up_var() to wake up the waiter when the count drops to zero. This uses the global wait queue hash table, avoiding the need to bloat struct tipc_net with a wait_queue_head_t. The atomic_dec_and_test() provides the necessary memory barrier to ensure the wakeup is not missed. | |
| Title | tipc: avoid busy looping in tipc_exit_net() | |
| First Time appeared |
Linux
Linux linux Kernel |
|
| CPEs | cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* | |
| Vendors & Products |
Linux
Linux linux Kernel |
|
| References |
|
MITRE
Status: PUBLISHED
Assigner: Linux
Published:
Updated: 2026-09-04T16:48:11.682Z
Reserved: 2026-08-26T14:34:25.798Z
Link: CVE-2026-80866
Vulnrichment
No data.
NVD
Status : Received
Published: 2026-09-04T17:16:58.390
Modified: 2026-09-04T17:16:58.390
Link: CVE-2026-80866
Redhat
No data.
OpenCVE Enrichment
No data.
No weakness.