linux/drivers/net/ethernet/intel/i40e
Jacob Keller bbc4e7d273 i40e: fix race condition with PTP_TX_IN_PROGRESS bits
Hardware related to the i40e driver has a limitation on Tx PTP packets.
This requires us to limit the driver to timestamping a single packet at
once. This is done using a state bitlock which enforces that only one
timestamp request is honored at a time.

Unfortunately this suffers from a race condition. The bit lock is not
cleared until after skb_tstamp_tx() is called notifying applications of
a new Tx timestamp. Even a well behaved application sending only one
packet at a time and waiting for a response can wake up and send a new
timestamped packet request before the bit lock is cleared. This results
in needlessly dropping some Tx timestamp requests.

We can fix this by unlocking the state bit as soon as we read the
Timestamp register, as this is the first point at which it is safe to
timestamp another packet.

To avoid issues with the skb pointer, we'll use a copy of the pointer
and set the global variable in the driver structure to NULL first. This
ensures that the next timestamp request does not modify our local copy
of the skb pointer.

Now, a well behaved application which has at most one outstanding
timestamp request will not accidentally race with the driver unlock bit.
Obviously an application attempting to timestamp faster than one request
at a time will have some timestamp requests skipped. Unfortunately there
is nothing we can do about that.

Reported-by: David Mirabito <davidm@metamako.com>
Signed-off-by: Jacob Keller <jacob.e.keller@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
2017-05-31 03:03:33 -07:00
..
i40e_adminq_cmd.h i40e: new AQ commands 2017-04-19 17:04:06 -07:00
i40e_adminq.c i40e: reduce wait time for adminq command completion 2017-04-19 17:38:25 -07:00
i40e_adminq.h i40e: reduce wait time for adminq command completion 2017-04-19 17:38:25 -07:00
i40e_alloc.h
i40e_client.c i40e: use DECLARE_BITMAP for state fields 2017-04-30 04:48:13 -07:00
i40e_client.h i40e: KISS the client interface 2017-03-15 01:57:08 -07:00
i40e_common.c i40e: new AQ commands 2017-04-19 17:04:06 -07:00
i40e_dcb_nl.c i40e: Change some messages from info to debug only 2015-10-15 01:58:41 -07:00
i40e_dcb.c i40e: refactor DCB function 2016-02-16 19:04:08 -08:00
i40e_dcb.h i40e: Add parsing for CEE DCBX TLVs 2015-10-08 15:11:38 -07:00
i40e_debugfs.c i40e: use DECLARE_BITMAP for state fields 2017-04-30 04:48:13 -07:00
i40e_devids.h i40e: Add support for 25G devices 2016-12-06 20:59:43 -08:00
i40e_diag.c
i40e_diag.h
i40e_ethtool.c i40e: remove hw_disabled_flags in favor of using separate flag bits 2017-04-30 04:53:58 -07:00
i40e_fcoe.c i40e: store MAC/VLAN filters in a hash with the MAC Address as key 2016-10-31 14:26:40 -07:00
i40e_fcoe.h
i40e_hmc.c i40e: fix an uninitialized variable bug 2016-05-14 00:21:51 -07:00
i40e_hmc.h
i40e_lan_hmc.c i40e: use explicit cast from u16 to u8 2015-12-12 21:08:26 -08:00
i40e_lan_hmc.h
i40e_main.c i40e: remove hw_disabled_flags in favor of using separate flag bits 2017-04-30 04:53:58 -07:00
i40e_nvm.c i40e: Acquire NVM lock before reads on all devices 2017-03-14 17:52:32 -07:00
i40e_osdep.h i40e: Drop FCoE code from core driver files 2017-03-27 16:47:43 -07:00
i40e_prototype.h i40e: new AQ commands 2017-04-19 17:04:06 -07:00
i40e_ptp.c i40e: fix race condition with PTP_TX_IN_PROGRESS bits 2017-05-31 03:03:33 -07:00
i40e_register.h i40e: Expose some registers to program parser, FD and RSS logic 2016-02-18 23:49:31 -08:00
i40e_status.h
i40e_trace.h i40e/i40evf: Add tracepoints 2017-04-19 16:47:31 -07:00
i40e_txrx.c i40e: remove hw_disabled_flags in favor of using separate flag bits 2017-04-30 04:53:58 -07:00
i40e_txrx.h i40e/i40evf: Add support for padding start of frames 2017-04-08 02:53:51 -07:00
i40e_type.h i40e: new AQ commands 2017-04-19 17:04:06 -07:00
i40e_virtchnl_pf.c i40e: use DECLARE_BITMAP for state fields 2017-04-30 04:48:13 -07:00
i40e_virtchnl_pf.h i40e: make use of i40e_reset_all_vfs when initializing new VFs 2017-04-30 04:05:20 -07:00
i40e_virtchnl.h i40e/i40evf: Add capability exchange for outer checksum 2017-04-06 20:14:51 -07:00
i40e.h i40e: remove hw_disabled_flags in favor of using separate flag bits 2017-04-30 04:53:58 -07:00
Makefile i40e/i40evf: Add tracepoints 2017-04-19 16:47:31 -07:00