/* * The owner field of the rw_semaphore structure will be set to * RWSEM_READ_OWNED when a reader grabs the lock. A writer will clear * the owner field when it unlocks. A reader, on the other hand, will * not touch the owner field when it unlocks. * * In essence, the owner field now has the following 3 states: * 1) 0 * - lock is free or the owner hasn't set the field yet * 2) RWSEM_READER_OWNED * - lock is currently or previously owned by readers (lock is free * or not set by owner yet) * 3) Other non-zero value * - a writer owns the lock */ #define RWSEM_READER_OWNED ((struct task_struct *)1UL) #ifdef CONFIG_RWSEM_SPIN_ON_OWNER /* * All writes to owner are protected by WRITE_ONCE() to make sure that * store tearing can't happen as optimistic spinners may read and use * the owner value concurrently without lock. Read from owner, however, * may not need READ_ONCE() as long as the pointer value is only used * for comparison and isn't being dereferenced. */ static inline void rwsem_set_owner(struct rw_semaphore *sem) { WRITE_ONCE(sem->owner, current); } static inline void rwsem_clear_owner(struct rw_semaphore *sem) { WRITE_ONCE(sem->owner, NULL); } static inline void rwsem_set_reader_owned(struct rw_semaphore *sem) { /* * We check the owner value first to make sure that we will only * do a write to the rwsem cacheline when it is really necessary * to minimize cacheline contention. */ if (sem->owner != RWSEM_READER_OWNED) WRITE_ONCE(sem->owner, RWSEM_READER_OWNED); } static inline bool rwsem_owner_is_writer(struct task_struct *owner) { return owner && owner != RWSEM_READER_OWNED; } static inline bool rwsem_owner_is_reader(struct task_struct *owner) { return owner == RWSEM_READER_OWNED; } #else static inline void rwsem_set_owner(struct rw_semaphore *sem) { } static inline void rwsem_clear_owner(struct rw_semaphore *sem) { } static inline void rwsem_set_reader_owned(struct rw_semaphore *sem) { } #endif x/net-next.git/commit/net/ipx/Kconfig?h=nds-private-remove&id=78794d1890708cf94e3961261e52dcec2cc34722'>commitdiff
path: root/net/ipx/Kconfig
diff options
context:
space:
mode:
authorJ. Bruce Fields <bfields@redhat.com>2017-01-09 17:15:18 -0500
committerJ. Bruce Fields <bfields@redhat.com>2017-01-12 15:56:14 -0500
commit78794d1890708cf94e3961261e52dcec2cc34722 (patch)
treeade1523bd1d3ebd2dc14e46676d496a2df16f116 /net/ipx/Kconfig
parentdcd208697707b12adeaa45643bab239c5e90ef9b (diff)
svcrpc: don't leak contexts on PROC_DESTROY
Context expiry times are in units of seconds since boot, not unix time. The use of get_seconds() here therefore sets the expiry time decades in the future. This prevents timely freeing of contexts destroyed by client RPC_GSS_PROC_DESTROY requests. We'd still free them eventually (when the module is unloaded or the container shut down), but a lot of contexts could pile up before then. Cc: stable@vger.kernel.org Fixes: c5b29f885afe "sunrpc: use seconds since boot in expiry cache" Reported-by: Andy Adamson <andros@netapp.com> Signed-off-by: J. Bruce Fields <bfields@redhat.com>
Diffstat (limited to 'net/ipx/Kconfig')