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4020272933
improve performance: - Eliminate custom reference count and condition variable to monitor threads entering the framework, as this had both significant overhead and behaved badly in the face of contention. - Replace reference count with two locks: an rwlock and an sx lock, which will be read-acquired by threads entering the framework depending on whether a give policy entry point is permitted to sleep or not. - Replace previous mutex locking of the reference count for exclusive access with write acquiring of both the policy list sx and rw locks, which occurs only when policies are attached or detached. - Do a lockless read of the dynamic policy list head before acquiring any locks in order to reduce overhead when no dynamic policies are loaded; this a race we can afford to lose. - For every policy entry point invocation, decide whether sleeping is permitted, and if not, use a _NOSLEEP() variant of the composition macros, which will use the rwlock instead of the sxlock. In some cases, we decide which to use based on allocation flags passed to the MAC Framework entry point. As with the move to rwlocks/rmlocks in pfil, this may trigger witness warnings, but these should (generally) be false positives as all acquisition of the locks is for read with two very narrow exceptions for policy load/unload, and those code blocks should never acquire other locks. Sponsored by: Google, Inc. Obtained from: TrustedBSD Project Discussed with: csjp (idea, not specific patch) |
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| .. | ||
| mac_atalk.c | ||
| mac_audit.c | ||
| mac_cred.c | ||
| mac_framework.c | ||
| mac_framework.h | ||
| mac_inet6.c | ||
| mac_inet.c | ||
| mac_internal.h | ||
| mac_label.c | ||
| mac_net.c | ||
| mac_pipe.c | ||
| mac_policy.h | ||
| mac_posix_sem.c | ||
| mac_posix_shm.c | ||
| mac_priv.c | ||
| mac_process.c | ||
| mac_socket.c | ||
| mac_syscalls.c | ||
| mac_system.c | ||
| mac_sysv_msg.c | ||
| mac_sysv_sem.c | ||
| mac_sysv_shm.c | ||
| mac_vfs.c | ||