2fe7e6f7c9
In addition to being overly complex, the locking in user_mad.c is broken: there were multiple reports of deadlocks and lockdep warnings. In particular it seems that a single thread may end up trying to take the same rwsem for reading more than once, which is explicitly forbidden in the comments in <linux/rwsem.h>. To solve this, we change the locking to use plain mutexes instead of rwsems. There is one mutex per open file, which protects the contents of the struct ib_umad_file, including the array of agents and list of queued packets; and there is one mutex per struct ib_umad_port, which protects the contents, including the list of open files. We never hold the file mutex across calls to functions like ib_unregister_mad_agent(), which can call back into other ib_umad code to queue a packet, and we always hold the port mutex as long as we need to make sure that a device is not hot-unplugged from under us. This even makes things nicer for users of the -rt patch, since we remove calls to downgrade_write() (which is not implemented in -rt). Signed-off-by: Roland Dreier <rolandd@cisco.com> |
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.. | ||
addr.c | ||
agent.c | ||
agent.h | ||
cache.c | ||
cm_msgs.h | ||
cm.c | ||
cma.c | ||
core_priv.h | ||
device.c | ||
fmr_pool.c | ||
iwcm.c | ||
iwcm.h | ||
mad_priv.h | ||
mad_rmpp.c | ||
mad_rmpp.h | ||
mad.c | ||
Makefile | ||
multicast.c | ||
packer.c | ||
sa_query.c | ||
sa.h | ||
smi.c | ||
smi.h | ||
sysfs.c | ||
ucm.c | ||
ucma.c | ||
ud_header.c | ||
umem.c | ||
user_mad.c | ||
uverbs_cmd.c | ||
uverbs_main.c | ||
uverbs_marshall.c | ||
uverbs.h | ||
verbs.c |