BMC/Intel-BMC/linux.git/drivers/infiniband/ulp/ipoib/ipoib.h, branch dev

IB/ipoib: Scatter-Gather support in connected mode

2015-07-14T17:20:13+00:00

By default, IPoIB-CM driver uses 64k MTU. Larger MTU gives better performance. This MTU plus overhead puts the memory allocation for IP based packets at 32 4k pages (order 5), which have to be contiguous. When the system memory under pressure, it was observed that allocating 128k contiguous physical memory is difficult and causes serious errors (such as system becomes unusable). This enhancement resolve the issue by removing the physically contiguous memory requirement using Scatter/Gather feature that exists in Linux stack. With this fix Scatter-Gather will be supported also in connected mode. This change reverts some of the change made in commit e112373fd6aa ("IPoIB/cm: Reduce connected mode TX object size"). The ability to use SG in IPoIB CM is possible because the coupling between NETIF_F_SG and NETIF_F_CSUM was removed in commit ec5f06156423 ("net: Kill link between CSUM and SG features.") Signed-off-by: Yuval Shaia Acked-by: Christian Marie Signed-off-by: Doug Ledford

IB/ipoib: Remove IPOIB_MCAST_RUN bit

2015-04-15T20:06:19+00:00

After Doug Ledford's changes there is no need in that bit, it's semantic becomes subset of the IPOIB_FLAG_OPER_UP bit. Signed-off-by: Erez Shitrit Signed-off-by: Or Gerlitz Signed-off-by: Doug Ledford

IB/ipoib: Handle QP in SQE state

2015-04-15T20:06:19+00:00

As the result of a completion error the QP can moved to SQE state by the hardware. Since it's not the Error state, there are no flushes and hence the driver doesn't know about that. The fix creates a task that after completion with error which is not a flush tracks the QP state and if it is in SQE state moves it back to RTS. Signed-off-by: Erez Shitrit Signed-off-by: Or Gerlitz Signed-off-by: Doug Ledford

IB/ipoib: Use one linear skb in RX flow

2015-04-15T20:06:18+00:00

The current code in the RX flow uses two sg entries for each incoming packet, the first one was for the IB headers and the second for the rest of the data, that causes two dma map/unmap and two allocations, and few more actions that were done at the data path. Use only one linear skb on each incoming packet, for the data (IB headers and payload), that reduces the packet processing in the data-path (only one skb, no frags, the first frag was not used anyway, less memory allocations) and the dma handling (only one dma map/unmap over each incoming packet instead of two map/unmap per each incoming packet). After commit 73d3fe6d1c6d ("gro: fix aggregation for skb using frag_list") from Eric Dumazet, we will get full aggregation for large packets. When running bandwidth tests before and after the (over the card's numa node), using "netperf -H 1.1.1.3 -T -t TCP_STREAM", the results before are ~12Gbs before and after ~16Gbs on my setup (Mellanox's ConnectX3). Signed-off-by: Erez Shitrit Signed-off-by: Or Gerlitz Signed-off-by: Doug Ledford

IB/ipoib: fix MCAST_FLAG_BUSY usage

2015-04-15T20:06:18+00:00

Commit a9c8ba5884 ("IPoIB: Fix usage of uninitialized multicast objects") added a new flag MCAST_JOIN_STARTED, but was not very strict in how it was used. We didn't always initialize the completion struct before we set the flag, and we didn't always call complete on the completion struct from all paths that complete it. And when we did complete it, sometimes we continued to touch the mcast entry after the completion, opening us up to possible use after free issues. This made it less than totally effective, and certainly made its use confusing. And in the flush function we would use the presence of this flag to signal that we should wait on the completion struct, but we never cleared this flag, ever. In order to make things clearer and aid in resolving the rtnl deadlock bug I've been chasing, I cleaned this up a bit. 1) Remove the MCAST_JOIN_STARTED flag entirely 2) Change MCAST_FLAG_BUSY so it now only means a join is in-flight 3) Test mcast->mc directly to see if we have completed ib_sa_join_multicast (using IS_ERR_OR_NULL) 4) Make sure that before setting MCAST_FLAG_BUSY we always initialize the mcast->done completion struct 5) Make sure that before calling complete(&mcast->done), we always clear the MCAST_FLAG_BUSY bit 6) Take the mcast_mutex before we call ib_sa_multicast_join and also take the mutex in our join callback. This forces ib_sa_multicast_join to return and set mcast->mc before we process the callback. This way, our callback can safely clear mcast->mc if there is an error on the join and we will do the right thing as a result in mcast_dev_flush. 7) Because we need the mutex to synchronize mcast->mc, we can no longer call mcast_sendonly_join directly from mcast_send and instead must add sendonly join processing to the mcast_join_task 8) Make MCAST_RUN mean that we have a working mcast subsystem, not that we have a running task. We know when we need to reschedule our join task thread and don't need a flag to tell us. 9) Add a helper for rescheduling the join task thread A number of different races are resolved with these changes. These races existed with the old MCAST_FLAG_BUSY usage, the MCAST_JOIN_STARTED flag was an attempt to address them, and while it helped, a determined effort could still trip things up. One race looks something like this: Thread 1 Thread 2 ib_sa_join_multicast (as part of running restart mcast task) alloc member call callback ifconfig ib0 down wait_for_completion callback call completes wait_for_completion in mcast_dev_flush completes mcast->mc is PTR_ERR_OR_NULL so we skip ib_sa_leave_multicast return from callback return from ib_sa_join_multicast set mcast->mc = return from ib_sa_multicast We now have a permanently unbalanced join/leave issue that trips up the refcounting in core/multicast.c Another like this: Thread 1 Thread 2 Thread 3 ib_sa_multicast_join ifconfig ib0 down priv->broadcast = NULL join_complete wait_for_completion mcast->mc is not yet set, so don't clear return from ib_sa_join_multicast and set mcast->mc complete return -EAGAIN (making mcast->mc invalid) call ib_sa_multicast_leave on invalid mcast->mc, hang forever By holding the mutex around ib_sa_multicast_join and taking the mutex early in the callback, we force mcast->mc to be valid at the time we run the callback. This allows us to clear mcast->mc if there is an error and the join is going to fail. We do this before we complete the mcast. In this way, mcast_dev_flush always sees consistent state in regards to mcast->mc membership at the time that the wait_for_completion() returns. Signed-off-by: Doug Ledford

IB/ipoib: No longer use flush as a parameter

2015-04-15T20:06:18+00:00

Various places in the IPoIB code had a deadlock related to flushing the ipoib workqueue. Now that we have per device workqueues and a specific flush workqueue, there is no longer a deadlock issue with flushing the device specific workqueues and we can do so unilaterally. Signed-off-by: Doug Ledford

IB/ipoib: Use dedicated workqueues per interface

2015-04-15T20:06:18+00:00

During my recent work on the rtnl lock deadlock in the IPoIB driver, I saw that even once I fixed the apparent races for a single device, as soon as that device had any children, new races popped up. It turns out that this is because no matter how well we protect against races on a single device, the fact that all devices use the same workqueue, and flush_workqueue() flushes *everything* from that workqueue means that we would also have to prevent all races between different devices (for instance, ipoib_mcast_restart_task on interface ib0 can race with ipoib_mcast_flush_dev on interface ib0.8002, resulting in a deadlock on the rtnl_lock). There are several possible solutions to this problem: Make carrier_on_task and mcast_restart_task try to take the rtnl for some set period of time and if they fail, then bail. This runs the real risk of dropping work on the floor, which can end up being its own separate kind of deadlock. Set some global flag in the driver that says some device is in the middle of going down, letting all tasks know to bail. Again, this can drop work on the floor. Or the method this patch attempts to use, which is when we bring an interface up, create a workqueue specifically for that interface, so that when we take it back down, we are flushing only those tasks associated with our interface. In addition, keep the global workqueue, but now limit it to only flush tasks. In this way, the flush tasks can always flush the device specific work queues without having deadlock issues. Signed-off-by: Doug Ledford

Revert "IPoIB: fix MCAST_FLAG_BUSY usage"

2015-01-30T23:39:20+00:00

This reverts commit 016d9fb25cd9817ea9c723f4f7ecd978636b4489. The series of IPoIB bug fixes that went into 3.19-rc1 introduce regressions, and after trying to sort things out, we decided to revert to 3.18's IPoIB driver and get things right for 3.20. Signed-off-by: Roland Dreier

Revert "IPoIB: Use dedicated workqueues per interface"

2015-01-30T23:38:55+00:00

This reverts commit 5141861cd5e17eac9676ff49c5abfafbea2b0e98. The series of IPoIB bug fixes that went into 3.19-rc1 introduce regressions, and after trying to sort things out, we decided to revert to 3.18's IPoIB driver and get things right for 3.20. Signed-off-by: Roland Dreier

Revert "IPoIB: Make ipoib_mcast_stop_thread flush the workqueue"

2015-01-30T23:38:46+00:00

This reverts commit bb42a6dd02fb2901a69dbec2358810735b14b186. The series of IPoIB bug fixes that went into 3.19-rc1 introduce regressions, and after trying to sort things out, we decided to revert to 3.18's IPoIB driver and get things right for 3.20. Signed-off-by: Roland Dreier