user/sven/linux.git/include/linux/netpoll.h, branch v3.10.49

netpoll: convert mutex into a semaphore

2013-05-01T19:00:24Z

Bart Van Assche recently reported a warning to me: [] warn_slowpath_common+0x7f/0xc0 [] warn_slowpath_null+0x1a/0x20 [] mutex_trylock+0x16d/0x180 [] netpoll_poll_dev+0x49/0xc30 [] ? __alloc_skb+0x82/0x2a0 [] netpoll_send_skb_on_dev+0x265/0x410 [] netpoll_send_udp+0x28a/0x3a0 [] ? write_msg+0x53/0x110 [netconsole] [] write_msg+0xcf/0x110 [netconsole] [] call_console_drivers.constprop.17+0xa1/0x1c0 [] console_unlock+0x2d6/0x450 [] vprintk_emit+0x1ee/0x510 [] printk+0x4d/0x4f [] scsi_print_command+0x7d/0xe0 [scsi_mod] This resulted from my commit ca99ca14c which introduced a mutex_trylock operation in a path that could execute in interrupt context. When mutex debugging is enabled, the above warns the user when we are in fact exectuting in interrupt context interrupt context. After some discussion, It seems that a semaphore is the proper mechanism to use here. While mutexes are defined to be unusable in interrupt context, no such condition exists for semaphores (save for the fact that the non blocking api calls, like up and down_trylock must be used when in irq context). Signed-off-by: Neil Horman Reported-by: Bart Van Assche CC: Bart Van Assche CC: David Miller CC: netdev@vger.kernel.org Signed-off-by: David S. Miller

netpoll: Fix __netpoll_rcu_free so that it can hold the rtnl lock

2013-02-12T00:19:33Z

__netpoll_rcu_free is used to free netpoll structures when the rtnl_lock is already held. The mechanism is used to asynchronously call __netpoll_cleanup outside of the holding of the rtnl_lock, so as to avoid deadlock. Unfortunately, __netpoll_cleanup modifies pointers (dev->np), which means the rtnl_lock must be held while calling it. Further, it cannot be held, because rcu callbacks may be issued in softirq contexts, which cannot sleep. Fix this by converting the rcu callback to a work queue that is guaranteed to get scheduled in process context, so that we can hold the rtnl properly while calling __netpoll_cleanup Tested successfully by myself. Signed-off-by: Neil Horman CC: "David S. Miller" CC: Cong Wang CC: Eric Dumazet Signed-off-by: David S. Miller

netpoll: protect napi_poll and poll_controller during dev_[open|close]

2013-02-06T20:45:03Z

Ivan Vercera was recently backporting commit 9c13cb8bb477a83b9a3c9e5a5478a4e21294a760 to a RHEL kernel, and I noticed that, while this patch protects the tg3 driver from having its ndo_poll_controller routine called during device initalization, it does nothing for the driver during shutdown. I.e. it would be entirely possible to have the ndo_poll_controller method (or subsequently the ndo_poll) routine called for a driver in the netpoll path on CPU A while in parallel on CPU B, the ndo_close or ndo_open routine could be called. Given that the two latter routines tend to initizlize and free many data structures that the former two rely on, the result can easily be data corruption or various other crashes. Furthermore, it seems that this is potentially a problem with all net drivers that support netpoll, and so this should ideally be fixed in a common path. As Ben H Pointed out to me, we can't preform dev_open/dev_close in atomic context, so I've come up with this solution. We can use a mutex to sleep in open/close paths and just do a mutex_trylock in the napi poll path and abandon the poll attempt if we're locked, as we'll just retry the poll on the next send anyway. I've tested this here by flooding netconsole with messages on a system whos nic driver I modfied to periodically return NETDEV_TX_BUSY, so that the netpoll tx workqueue would be forced to send frames and poll the device. While this was going on I rapidly ifdown/up'ed the interface and watched for any problems. I've not found any. Signed-off-by: Neil Horman CC: Ivan Vecera CC: "David S. Miller" CC: Ben Hutchings CC: Francois Romieu CC: Eric Dumazet Signed-off-by: David S. Miller

netpoll: prepare for ipv6

2013-01-09T01:56:09Z

This patch adjusts some struct and functions, to prepare for supporting IPv6. Cc: David S. Miller Signed-off-by: Cong Wang Signed-off-by: David S. Miller

netpoll: convert several functions to bool

2012-08-14T21:33:32Z

These functions are just boolean, let them return bool instead of int. Cc: David Miller Signed-off-by: Cong Wang Signed-off-by: David S. Miller

netpoll: take rcu_read_lock_bh() in netpoll_send_skb_on_dev()

2012-08-14T21:33:31Z

This patch fixes several problems in the call path of netpoll_send_skb_on_dev(): 1. Disable IRQ's before calling netpoll_send_skb_on_dev(). 2. All the callees of netpoll_send_skb_on_dev() should use rcu_dereference_bh() to dereference ->npinfo. 3. Rename arp_reply() to netpoll_arp_reply(), the former is too generic. Cc: "David S. Miller" Signed-off-by: Cong Wang Signed-off-by: David S. Miller

netpoll: use netpoll_rx_on() in netpoll_rx()

2012-08-14T21:33:31Z

The logic of the code is same, just call netpoll_rx_on(). Cc: "David S. Miller" Signed-off-by: Cong Wang Signed-off-by: David S. Miller

netpoll: take rcu_read_lock_bh() in netpoll_rx()

2012-08-14T21:33:31Z

In __netpoll_rx(), it dereferences ->npinfo without rcu_dereference_bh(), this patch fixes it by using the 'npinfo' passed from netpoll_rx() where it is already dereferenced with rcu_dereference_bh(). Cc: "David S. Miller" Signed-off-by: Cong Wang Signed-off-by: David S. Miller

netpoll: make __netpoll_cleanup non-block

2012-08-14T21:33:30Z

Like the previous patch, slave_disable_netpoll() and __netpoll_cleanup() may be called with read_lock() held too, so we should make them non-block, by moving the cleanup and kfree() to call_rcu_bh() callbacks. Cc: "David S. Miller" Signed-off-by: Cong Wang Signed-off-by: David S. Miller

netpoll: use GFP_ATOMIC in slave_enable_netpoll() and __netpoll_setup()

2012-08-14T21:33:30Z

slave_enable_netpoll() and __netpoll_setup() may be called with read_lock() held, so should use GFP_ATOMIC to allocate memory. Eric suggested to pass gfp flags to __netpoll_setup(). Cc: Eric Dumazet Cc: "David S. Miller" Reported-by: Dan Carpenter Signed-off-by: Eric Dumazet Signed-off-by: Cong Wang Signed-off-by: David S. Miller