Module Name: src
Committed By: knakahara
Date: Fri Feb 17 11:57:26 UTC 2017
Modified Files:
src/sys/dev/pci: if_wm.c
Log Message:
rxq_ptr must be updated holding rxq_lock consistent with the Rx processing.
In previous implementation, wm_rxeof() temporarily unlock rxq->rxq_lock to
call if_percpuq_enqueue(), and then re-lock rxq->rxq_lock to update
rxq->rxq_ptr. So, if multiple CPUs share the same rxq, there is race e.g.
- CPU A: lock rxq->rxq_lock
- CPU A: Rx processing include increment local variable "i"
- CPU A: unlock rxq->rxq_lock
- CPU A: call if_percpuq_enqueue()
- CPU B: lock rxq->rxq_lock
- CPU B: Rx processing include increment local variable "i"
- CPU B: unlock rxq->rxq_lock
- CPU B: call if_percpuq_enqueue()
- CPU B: lock rxq->rxq_lock
- CPU B: update rxq->rxq_ptr, that is, set CPU B's local "i" to rxq->rxq_ptr
- CPU B: unlock rxq->rxq_lock
- CPU A: lock rxq->rxq_lock
- CPU A: update rxq->rxq_ptr, that is, set CPU A's local "i" to rxq->rxq_ptr
- CPU A: unlock rxq->rxq_lock
To generate a diff of this commit:
cvs rdiff -u -r1.482 -r1.483 src/sys/dev/pci/if_wm.c
Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.
