user/sven/linux.git/include/linux/dsa, branch v5.6.10

net: dsa: tag_8021q: replace dsa_8021q_remove_header with __skb_vlan_pop

2020-03-24T23:19:01Z

Not only did this wheel did not need reinventing, but there is also an issue with it: It doesn't remove the VLAN header in a way that preserves the L2 payload checksum when that is being provided by the DSA master hw. It should recalculate checksum both for the push, before removing the header, and for the pull afterwards. But the current implementation is quite dizzying, with pulls followed immediately afterwards by pushes, the memmove is done before the push, etc. This makes a DSA master with RX checksumming offload to print stack traces with the infamous 'hw csum failure' message. So remove the dsa_8021q_remove_header function and replace it with something that actually works with inet checksumming. Fixes: d461933638ae ("net: dsa: tag_8021q: Create helper function for removing VLAN header") Signed-off-by: Vladimir Oltean Signed-off-by: David S. Miller

net: dsa: Make deferred_xmit private to sja1105

2020-01-05T23:13:13Z

There are 3 things that are wrong with the DSA deferred xmit mechanism: 1. Its introduction has made the DSA hotpath ever so slightly more inefficient for everybody, since DSA_SKB_CB(skb)->deferred_xmit needs to be initialized to false for every transmitted frame, in order to figure out whether the driver requested deferral or not (a very rare occasion, rare even for the only driver that does use this mechanism: sja1105). That was necessary to avoid kfree_skb from freeing the skb. 2. Because L2 PTP is a link-local protocol like STP, it requires management routes and deferred xmit with this switch. But as opposed to STP, the deferred work mechanism needs to schedule the packet rather quickly for the TX timstamp to be collected in time and sent to user space. But there is no provision for controlling the scheduling priority of this deferred xmit workqueue. Too bad this is a rather specific requirement for a feature that nobody else uses (more below). 3. Perhaps most importantly, it makes the DSA core adhere a bit too much to the NXP company-wide policy "Innovate Where It Doesn't Matter". The sja1105 is probably the only DSA switch that requires some frames sent from the CPU to be routed to the slave port via an out-of-band configuration (register write) rather than in-band (DSA tag). And there are indeed very good reasons to not want to do that: if that out-of-band register is at the other end of a slow bus such as SPI, then you limit that Ethernet flow's throughput to effectively the throughput of the SPI bus. So hardware vendors should definitely not be encouraged to design this way. We do _not_ want more widespread use of this mechanism. Luckily we have a solution for each of the 3 issues: For 1, we can just remove that variable in the skb->cb and counteract the effect of kfree_skb with skb_get, much to the same effect. The advantage, of course, being that anybody who doesn't use deferred xmit doesn't need to do any extra operation in the hotpath. For 2, we can create a kernel thread for each port's deferred xmit work. If the user switch ports are named swp0, swp1, swp2, the kernel threads will be named swp0_xmit, swp1_xmit, swp2_xmit (there appears to be a 15 character length limit on kernel thread names). With this, the user can change the scheduling priority with chrt $(pidof swp2_xmit). For 3, we can actually move the entire implementation to the sja1105 driver. So this patch deletes the generic implementation from the DSA core and adds a new one, more adequate to the requirements of PTP TX timestamping, in sja1105_main.c. Suggested-by: Florian Fainelli Signed-off-by: Vladimir Oltean Reviewed-by: Florian Fainelli Signed-off-by: David S. Miller

net: dsa: sja1105: Always send through management routes in slot 0

2020-01-05T23:13:12Z

I finally found out how the 4 management route slots are supposed to be used, but.. it's not worth it. The description from the comment I've just deleted in this commit is still true: when more than 1 management slot is active at the same time, the switch will match frames incoming [from the CPU port] on the lowest numbered management slot that matches the frame's DMAC. My issue was that one was not supposed to statically assign each port a slot. Yes, there are 4 slots and also 4 non-CPU ports, but that is a mere coincidence. Instead, the switch can be used like this: every management frame gets a slot at the right of the most recently assigned slot: Send mgmt frame 1 through S0: S0 x x x Send mgmt frame 2 through S1: S0 S1 x x Send mgmt frame 3 through S2: S0 S1 S2 x Send mgmt frame 4 through S3: S0 S1 S2 S3 The difference compared to the old usage is that the transmission of frames 1-4 doesn't need to wait until the completion of the management route. It is safe to use a slot to the right of the most recently used one, because by protocol nobody will program a slot to your left and "steal" your route towards the correct egress port. So there is a potential throughput benefit here. But mgmt frame 5 has no more free slot to use, so it has to wait until _all_ of S0, S1, S2, S3 are full, in order to use S0 again. And that's actually exactly the problem: I was looking for something that would bring more predictable transmission latency, but this is exactly the opposite: 3 out of 4 frames would be transmitted quicker, but the 4th would draw the short straw and have a worse worst-case latency than before. Useless. Things are made even worse by PTP TX timestamping, which is something I won't go deeply into here. Suffice to say that the fact there is a driver-level lock on the SPI bus offsets any potential throughput gains that parallelism might bring. So there's no going back to the multi-slot scheme, remove the "mgmt_slot" variable from sja1105_port and the dummy static assignment made at probe time. While passing by, also remove the assignment to casc_port altogether. Don't pretend that we support cascaded setups. Signed-off-by: Vladimir Oltean Reviewed-by: Florian Fainelli Signed-off-by: David S. Miller

net: dsa: sja1105: Use PTP core's dedicated kernel thread for RX timestamping

2019-12-31T04:31:40Z

And move the queue of skb's waiting for RX timestamps into the ptp_data structure, since it isn't needed if PTP is not compiled. Signed-off-by: Vladimir Oltean Signed-off-by: David S. Miller

net: dsa: sja1105: Fix sleeping while atomic in .port_hwtstamp_set

2019-10-02T16:19:53Z

Currently this stack trace can be seen with CONFIG_DEBUG_ATOMIC_SLEEP=y: [ 41.568348] BUG: sleeping function called from invalid context at kernel/locking/mutex.c:909 [ 41.576757] in_atomic(): 1, irqs_disabled(): 0, pid: 208, name: ptp4l [ 41.583212] INFO: lockdep is turned off. [ 41.587123] CPU: 1 PID: 208 Comm: ptp4l Not tainted 5.3.0-rc6-01445-ge950f2d4bc7f-dirty #1827 [ 41.599873] [] (unwind_backtrace) from [] (show_stack+0x10/0x14) [ 41.607584] [] (show_stack) from [] (dump_stack+0xd4/0x100) [ 41.614863] [] (dump_stack) from [] (___might_sleep+0x1c8/0x2b4) [ 41.622574] [] (___might_sleep) from [] (__mutex_lock+0x48/0xab8) [ 41.630368] [] (__mutex_lock) from [] (mutex_lock_nested+0x1c/0x24) [ 41.638340] [] (mutex_lock_nested) from [] (sja1105_static_config_reload+0x30/0x27c) [ 41.647779] [] (sja1105_static_config_reload) from [] (sja1105_hwtstamp_set+0x108/0x1cc) [ 41.657562] [] (sja1105_hwtstamp_set) from [] (dev_ifsioc+0x18c/0x330) [ 41.665788] [] (dev_ifsioc) from [] (dev_ioctl+0x320/0x6e8) [ 41.673064] [] (dev_ioctl) from [] (sock_ioctl+0x334/0x5e8) [ 41.680340] [] (sock_ioctl) from [] (do_vfs_ioctl+0xb0/0xa10) [ 41.687789] [] (do_vfs_ioctl) from [] (ksys_ioctl+0x34/0x58) [ 41.695151] [] (ksys_ioctl) from [] (ret_fast_syscall+0x0/0x28) [ 41.702768] Exception stack(0xe8495fa8 to 0xe8495ff0) [ 41.707796] 5fa0: beff4a8c 00000001 00000011 000089b0 beff4a8c beff4a80 [ 41.715933] 5fc0: beff4a8c 00000001 0000000c 00000036 b6fa98c8 004e19c1 00000001 00000000 [ 41.724069] 5fe0: 004dcedc beff4a6c 004c0738 b6e7af4c [ 41.729860] BUG: scheduling while atomic: ptp4l/208/0x00000002 [ 41.735682] INFO: lockdep is turned off. Enabling RX timestamping will logically disturb the fastpath (processing of meta frames). Replace bool hwts_rx_en with a bit that is checked atomically from the fastpath and temporarily unset from the sleepable context during a change of the RX timestamping process (a destructive operation anyways, requires switch reset). If found unset, the fastpath (net/dsa/tag_sja1105.c) will just drop any received meta frame and not take the meta_lock at all. Fixes: a602afd200f5 ("net: dsa: sja1105: Expose PTP timestamping ioctls to userspace") Signed-off-by: Vladimir Oltean Signed-off-by: David S. Miller

net: dsa: sja1105: Add a state machine for RX timestamping

2019-06-08T22:20:40Z

Meta frame reception relies on the hardware keeping its promise that it will send no other traffic towards the CPU port between a link-local frame and a meta frame. Otherwise there is no other way to associate the meta frame with the link-local frame it's holding a timestamp of. The receive function is made stateful, and buffers a timestampable frame until its meta frame arrives, then merges the two, drops the meta and releases the link-local frame up the stack. Signed-off-by: Vladimir Oltean Signed-off-by: David S. Miller

net: dsa: sja1105: Add a global sja1105_tagger_data structure

2019-06-08T22:20:40Z

This will be used to keep state for RX timestamping. It is global because the switch serializes timestampable and meta frames when trapping them towards the CPU port (lower port indices have higher priority) and therefore having one state machine per port would create unnecessary complications. Signed-off-by: Vladimir Oltean Signed-off-by: David S. Miller

net: dsa: sja1105: Build a minimal understanding of meta frames

2019-06-08T22:20:40Z

Meta frames are sent on the CPU port by the switch if RX timestamping is enabled. They contain a partial timestamp of the previous frame. They are Ethernet frames with the Ethernet header constructed out of: - SJA1105_META_DMAC - SJA1105_META_SMAC - ETH_P_SJA1105_META The Ethernet payload will be decoded in a follow-up patch. Signed-off-by: Vladimir Oltean Reviewed-by: Florian Fainelli Signed-off-by: David S. Miller

net: dsa: sja1105: Add logic for TX timestamping

2019-06-08T22:20:40Z

On TX, timestamping is performed synchronously from the port_deferred_xmit worker thread. In management routes, the switch is requested to take egress timestamps (again partial), which are reconstructed and appended to a clone of the skb that was just sent. The cloning is done by DSA and we retrieve the pointer from the structure that DSA keeps in skb->cb. Then these clones are enqueued to the socket's error queue for application-level processing. Signed-off-by: Vladimir Oltean Signed-off-by: David S. Miller

net: dsa: tag_8021q: Create helper function for removing VLAN header

2019-06-08T22:20:39Z

This removes the existing implementation from tag_sja1105, which was partially incorrect (it was not changing the MAC header offset, thereby leaving it to point 4 bytes earlier than it should have). This overwrites the VLAN tag by moving the Ethernet source and destination MACs 4 bytes to the right. Then skb->data (assumed to be pointing immediately after the EtherType) is temporarily pushed to the beginning of the new Ethernet header, the new Ethernet header offset and length are recorded, then skb->data is moved back to where it was. Signed-off-by: Vladimir Oltean Signed-off-by: David S. Miller