I just updated Documentation/networking/netdevices.txt locally to the
attached file, which describes the synchronization rules for net drivers
in the 2.4.x and 2.5.x kernels. (Astute readers will notice a striking
similarity to 2.2.x locking rules as well)
Comments and corrections to the attached doc requested. I realize it's
not much right now, but this is core info I want to make sure is
correct, and that everyone agrees on.
Thanks to Robert Olsson for a pointer about dev->poll().
Future notes: this doc will hopefully expand in time to describe not
only the netdevice API but also standard ethernet and net driver
practices. Patches welcome!
Jeff
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Network Devices, the Kernel, and You!
Introduction
============
The following is a random collection of documentation regarding
network devices.
struct net_device synchronization rules
=======================================
dev->open:
Synchronization: rtnl_lock() semaphore.
Context: process
dev->stop:
Synchronization: rtnl_lock() semaphore.
Context: process
Notes: netif_running() is guaranteed false when this is called
dev->do_ioctl:
Synchronization: rtnl_lock() semaphore.
Context: process
dev->get_stats:
Synchronization: dev_base_lock rwlock.
Context: nominally process, but don't sleep inside an rwlock
dev->hard_start_xmit:
Synchronization: dev->xmit_lock spinlock.
Context: BHs disabled
dev->tx_timeout:
Synchronization: dev->xmit_lock spinlock.
Context: BHs disabled
dev->set_multicast_list:
Synchronization: dev->xmit_lock spinlock.
Context: BHs disabled
dev->poll:
Synchronization: __LINK_STATE_RX_SCHED bit in dev->state. See
dev_close code and comments in net/core/dev.c for more info.
Context: softirq
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