#include #include #include /* * This is an implementation of the notion of "decrement a * reference count, and return locked if it decremented to zero". * * NOTE NOTE NOTE! This is _not_ equivalent to * * if (atomic_dec_and_test(&atomic)) { * spin_lock(&lock); * return 1; * } * return 0; * * because the spin-lock and the decrement must be * "atomic". */ int _atomic_dec_and_lock(atomic_t *atomic, spinlock_t *lock) { /* Subtract 1 from counter unless that drops it to 0 (ie. it was 1) */ if (atomic_add_unless(atomic, -1, 1)) return 0; /* Otherwise do it the slow way */ spin_lock(lock); if (atomic_dec_and_test(atomic)) return 1; spin_unlock(lock); return 0; } EXPORT_SYMBOL(_atomic_dec_and_lock); ain'>index : net-next.git
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authorDaniel Vetter <daniel.vetter@ffwll.ch>2016-12-18 14:35:45 +0100
committerDaniel Vetter <daniel.vetter@ffwll.ch>2017-01-30 10:17:17 +0100
commit4e5b54f127426c82dc2816340c26d951a5bb3429 (patch)
treecc3a8f7e335cf12880bc8d1a1e2066f6cfe0a68e /include/soc/at91
parent566cf877a1fcb6d6dc0126b076aad062054c2637 (diff)
drm: prevent double-(un)registration for connectors
If we're unlucky then the registration from a hotplugged connector might race with the final registration step on driver load. And since MST topology discover is asynchronous that's even somewhat likely. v2: Also update the kerneldoc for @registered! v3: Review from Chris: - Improve kerneldoc for late_register/early_unregister callbacks. - Use mutex_destroy. Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk> Cc: Chris Wilson <chris@chris-wilson.co.uk> Reviewed-by: Sean Paul <seanpaul@chromium.org> Reported-by: Chris Wilson <chris@chris-wilson.co.uk> Signed-off-by: Daniel Vetter <daniel.vetter@intel.com> Link: http://patchwork.freedesktop.org/patch/msgid/20161218133545.2106-1-daniel.vetter@ffwll.ch (cherry picked from commit e73ab00e9a0f1731f34d0620a9c55f5c30c4ad4e)
Diffstat (limited to 'include/soc/at91')