04 Nov, 2010
2 commits
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All the rds_tcp_connection objects are stored list, but when
being freed it should be removed from there.Signed-off-by: Pavel Emelyanov
Signed-off-by: David S. Miller -
The conn is removed from list in there and this requires
proper lock protection.Signed-off-by: Pavel Emelyanov
Signed-off-by: David S. Miller
31 Oct, 2010
5 commits
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Even with the previous fix, we still are reading the iovecs once
to determine SGs needed, and then again later on. Preallocating
space for sg lists as part of rds_message seemed like a good idea
but it might be better to not do this. While working to redo that
code, this patch attempts to protect against userspace rewriting
the rds_iovec array between the first and second accesses.The consequences of this would be either a too-small or too-large
sg list array. Too large is not an issue. This patch changes all
callers of message_alloc_sgs to handle running out of preallocated
sgs, and fail gracefully.Signed-off-by: Andy Grover
Signed-off-by: David S. Miller -
Change rds_rdma_pages to take a passed-in rds_iovec array instead
of doing copy_from_user itself.Change rds_cmsg_rdma_args to copy rds_iovec array once only. This
eliminates the possibility of userspace changing it after our
sanity checks.Implement stack-based storage for small numbers of iovecs, based
on net/socket.c, to save an alloc in the extremely common case.Although this patch reduces iovec copies in cmsg_rdma_args to 1,
we still do another one in rds_rdma_extra_size. Getting rid of
that one will be trickier, so it'll be a separate patch.Signed-off-by: Andy Grover
Signed-off-by: David S. Miller -
We don't need to set ret = 0 at the end -- it's initialized to 0.
Also, don't increment s_send_rdma stat if we're exiting with an
error.Signed-off-by: Andy Grover
Signed-off-by: David S. Miller -
rds_cmsg_rdma_args would still return success even if rds_rdma_pages
returned an error (or overflowed).Signed-off-by: Andy Grover
Signed-off-by: David S. Miller -
As reported by Thomas Pollet, the rdma page counting can overflow. We
get the rdma sizes in 64-bit unsigned entities, but then limit it to
UINT_MAX bytes and shift them down to pages (so with a possible "+1" for
an unaligned address).So each individual page count fits comfortably in an 'unsigned int' (not
even close to overflowing into signed), but as they are added up, they
might end up resulting in a signed return value. Which would be wrong.Catch the case of tot_pages turning negative, and return the appropriate
error code.Reported-by: Thomas Pollet
Signed-off-by: Linus Torvalds
Signed-off-by: Andy Grover
Signed-off-by: David S. Miller
21 Oct, 2010
2 commits
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Conflicts:
net/core/dev.c -
The RDS protocol has lots of functions that should be
declared static. rds_message_get/add_version_extension is
removed since it defined but never used.Signed-off-by: Stephen Hemminger
Signed-off-by: David S. Miller
16 Oct, 2010
1 commit
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Don't try to "optimize" rds_page_copy_user() by using kmap_atomic() and
the unsafe atomic user mode accessor functions. It's actually slower
than the straightforward code on any reasonable modern CPU.Back when the code was written (although probably not by the time it was
actually merged, though), 32-bit x86 may have been the dominant
architecture. And there kmap_atomic() can be a lot faster than kmap()
(unless you have very good locality, in which case the virtual address
caching by kmap() can overcome all the downsides).But these days, x86-64 may not be more populous, but it's getting there
(and if you care about performance, it's definitely already there -
you'd have upgraded your CPU's already in the last few years). And on
x86-64, the non-kmap_atomic() version is faster, simply because the code
is simpler and doesn't have the "re-try page fault" case.People with old hardware are not likely to care about RDS anyway, and
the optimization for the 32-bit case is simply buggy, since it doesn't
verify the user addresses properly.Reported-by: Dan Rosenberg
Acked-by: Andrew Morton
Cc: stable@kernel.org
Signed-off-by: Linus Torvalds
27 Sep, 2010
1 commit
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Conflicts:
drivers/net/qlcnic/qlcnic_init.c
net/ipv4/ip_output.c
25 Sep, 2010
1 commit
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We have for each socket :
One spinlock (sk_slock.slock)
One rwlock (sk_callback_lock)Possible scenarios are :
(A) (this is used in net/sunrpc/xprtsock.c)
read_lock(&sk->sk_callback_lock) (without blocking BH)spin_lock(&sk->sk_slock.slock);
...
read_lock(&sk->sk_callback_lock);
...(B)
write_lock_bh(&sk->sk_callback_lock)
stuff
write_unlock_bh(&sk->sk_callback_lock)(C)
spin_lock_bh(&sk->sk_slock)
...
write_lock_bh(&sk->sk_callback_lock)
stuff
write_unlock_bh(&sk->sk_callback_lock)
spin_unlock_bh(&sk->sk_slock)This (C) case conflicts with (A) :
CPU1 [A] CPU2 [C]
read_lock(callback_lock)
spin_lock_bh(slock)We have one problematic (C) use case in inet_csk_listen_stop() :
local_bh_disable();
bh_lock_sock(child); // spin_lock_bh(&sk->sk_slock)
WARN_ON(sock_owned_by_user(child));
...
sock_orphan(child); // write_lock_bh(&sk->sk_callback_lock)lockdep is not happy with this, as reported by Tetsuo Handa
It seems only way to deal with this is to use read_lock_bh(callbacklock)
everywhere.Thanks to Jarek for pointing a bug in my first attempt and suggesting
this solution.Reported-by: Tetsuo Handa
Tested-by: Tetsuo Handa
Signed-off-by: Eric Dumazet
CC: Jarek Poplawski
Tested-by: Eric Dumazet
Signed-off-by: David S. Miller
20 Sep, 2010
3 commits
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This is basically just a cleanup. IRQs were disabled on the previous
line so we don't need to do it again here. In the current code IRQs
would get turned on one line earlier than intended.Signed-off-by: Dan Carpenter
Signed-off-by: David S. Miller -
We unlock after we goto out.
Signed-off-by: Dan Carpenter
Signed-off-by: David S. Miller -
In the original code if the copy_from_user() fails in rds_rdma_pages()
then the error handling fails and we get a stack trace from kmalloc().Signed-off-by: Dan Carpenter
Signed-off-by: David S. Miller
09 Sep, 2010
25 commits
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Add two CMSGs for masked versions of cswp and fadd. args
struct modified to use a union for different atomic op type's
arguments. Change IB to do masked atomic ops. Atomic op type
in rds_message similarly unionized.Signed-off-by: Andy Grover
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This prints the constant identifier for work completion status and rdma
cm event types, like we already do for IB event types.A core string array helper is added that each string type uses.
Signed-off-by: Zach Brown
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Nothing was canceling the send and receive work that might have been
queued as a conn was being destroyed.Signed-off-by: Zach Brown
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rds_conn_shutdown() can return before the connection is shut down when
it encounters an existing state that it doesn't understand. This lets
rds_conn_destroy() then start tearing down the conn from under paths
that are still using it.It's more reliable the shutdown work and wait for krdsd to complete the
shutdown callback. This stopped some hangs I was seeing where krdsd was
trying to shut down a freed conn.Signed-off-by: Zach Brown
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Right now there's nothing to stop the various paths that use
rs->rs_transport from racing with rmmod and executing freed transport
code. The simple fix is to have binding to a transport also hold a
reference to the transport's module, removing this class of races.We already had an unused t_owner field which was set for the modular
transports and which wasn't set for the built-in loop transport.Signed-off-by: Zach Brown
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rs_transport is now also used by the rdma paths once the socket is
bound. We don't need this stale comment to tell us what cscope can.Signed-off-by: Zach Brown
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rds_conn_destroy() can race with all other modifications of the
rds_conn_count but it was modifying the count without locking.Signed-off-by: Zach Brown
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The RDS IB device list wasn't protected by any locking. Traversal in
both the get_mr and FMR flushing paths could race with additon and
removal.List manipulation is done with RCU primatives and is protected by the
write side of a rwsem. The list traversal in the get_mr fast path is
protected by a rcu read critical section. The FMR list traversal is
more problematic because it can block while traversing the list. We
protect this with the read side of the rwsem.Signed-off-by: Zach Brown
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It's nice to not have to go digging in the code to see which event
occurred. It's easy to throw together a quick array that maps the ib
event enums to their strings. I didn't see anything in the stack that
does this translation for us, but I also didn't look very hard.Signed-off-by: Zach Brown
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Flushing FMRs is somewhat expensive, and is currently kicked off when
the interrupt handler notices that we are getting low. The result of
this is that FMR flushing only happens from the interrupt cpus.This spreads the load more effectively by triggering flushes just before
we allocate a new FMR.Signed-off-by: Chris Mason
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This is only needed to keep debugging code from bugging.
Signed-off-by: Chris Mason
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We're seeing bugs today where IB connection shutdown clears the send
ring while the tasklet is processing completed sends. Implementation
details cause this to dereference a null pointer. Shutdown needs to
wait for send completion to stop before tearing down the connection. We
can't simply wait for the ring to empty because it may contain
unsignaled sends that will never be processed.This patch tracks the number of signaled sends that we've posted and
waits for them to complete. It also makes sure that the tasklet has
finished executing.Signed-off-by: Zach Brown
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The trivial amount of memory saved isn't worth the cost of dealing with section
mismatches.Signed-off-by: Zach Brown
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We are *definitely* counting cycles as closely as DaveM, so
ensure hwcache alignment for our recv ring control structs.Signed-off-by: Andy Grover
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The recv refill path was leaking fragments because the recv event handler had
marked a ring element as free without freeing its frag. This was happening
because it wasn't processing receives when the conn wasn't marked up or
connecting, as can be the case if it races with rmmod.Two observations support always processing receives in the callback.
First, buildup should only post receives, thus triggering recv event handler
calls, once it has built up all the state to handle them. Teardown should
destroy the CQ and drain the ring before tearing down the state needed to
process recvs. Both appear to be true today.Second, this test was fundamentally racy. There is nothing to stop rmmod and
connection destruction from swooping in the moment after the conn state was
sampled but before real receive procesing starts.Signed-off-by: Zach Brown
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We were seeing very nasty bugs due to fundamental assumption the current code
makes about concurrent work struct processing. The code simpy isn't able to
handle concurrent connection shutdown work function execution today, for
example, which is very much possible once a multi-threaded krdsd was
introduced. The problem compounds as additional work structs are added to the
mix.krdsd is no longer perforance critical now that send and receive posting and
FMR flushing are done elsewhere, so the safest fix is to move back to the
single threaded krdsd that the current code was built around.Signed-off-by: Zach Brown
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This patch moves the FMR flushing work in to its own mult-threaded work queue.
This is to maintain performance in preparation for returning the main krdsd
work queue back to a single threaded work queue to avoid deep-rooted
concurrency bugs.This is also good because it further separates FMRs, which might be removed
some day, from the rest of the code base.Signed-off-by: Zach Brown
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IB connections were not being destroyed during rmmod.
First, recently IB device removal callback was changed to disconnect
connections that used the removing device rather than destroying them. So
connections with devices during rmmod were not being destroyed.Second, rds_ib_destroy_nodev_conns() was being called before connections are
disassociated with devices. It would almost never find connections in the
nodev list.We first get rid of rds_ib_destroy_conns(), which is no longer called, and
refactor the existing caller into the main body of the function and get rid of
the list and lock wrappers.Then we call rds_ib_destroy_nodev_conns() *after* ib_unregister_client() has
removed the IB device from all the conns and put the conns on the nodev list.The result is that IB connections are destroyed by rmmod.
Signed-off-by: Zach Brown
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The RDS IB client removal callback can queue work to drop the final reference
to an IB device. We have to make sure that this function has returned before
we complete rmmod or the work threads can try to execute freed code.Signed-off-by: Zach Brown
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Signed-off-by: Andy Grover
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Not used.
Signed-off-by: Andy Grover
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Using a delayed work queue helps us make sure a healthy number of FMRs
have queued up over the limit. It makes for a large improvement in RDMA
iops.Signed-off-by: Chris Mason
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When we add more FMRs, we flush them less often and so we go faster.
Signed-off-by: Chris Mason
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FRM allocation and recycling is performance critical and fairly lock
intensive. The current code has a per connection lock that all
processes bang on and it becomes a major bottleneck on large systems.This changes things to use a number of cmpxchg based lists instead,
allowing us to go through the whole FMR lifecycle without locking inside
RDS.Zach Brown pointed out that our usage of cmpxchg for xlist removal is
racey if someone manages to remove and add back an FMR struct into the list
while another CPU can see the FMR's address at the head of the list.The second CPU might assume the list hasn't changed when in fact any
number of operations might have happened in between the deletion and
reinsertion.This commit maintains a per cpu count of CPUs that are currently
in xlist removal, and establishes a grace period to make sure that
nobody can see an entry we have just removed from the list.Signed-off-by: Chris Mason
