Linaro-mm-sig February 2026

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CRYPTO ASSET RECOVERY 2026 RECLAIM LOST FUNDS SAFELY TODAY

by angelaasher62＠gmail.com

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Email: info(a)autopsymainnetsolutions.com Website: https://autospyrec.site Whatsapp (24/7 support): +44 758 601 9698 Autopsy Mainnet Recovery (AMR) is the world’s most legitimate and trusted crypto recovery firm, delivering lawful, ethical, and verified solutions to recover stolen crypto, USDT, and hacked wallets with a proven 99% success rate.

3 months

RECOVER SCAMMED CRYPTO COMPLETE 2026 GUIDE AND TRUSTED SOLUTIONS

by masoncaleb2a＠gmail.com

3 months

WHAT IS CRYPTO RECOVERY SECURE YOUR LOST CRYPTOCURRENCY TODAY

by aubreyasher46＠gmail.com

3 months

CRYPTO SCAM RECOVERY GUIDE STEPS TO RECLAIM FUNDS SAFELY 2026

by codykayson983＠gmail.com

3 months

How Can I Contact a Cryptocurrency Recovery Company? Employ iFORCE HACKER RECOVERY

by rubsmit280＠gmail.com

iFORCE HACKER RECOVERY is a professional cryptocurrency recovery agency that specializes in tracking down digital assets, recovering stolen USDT, and recovering misplaced Bitcoin. They assist in locating and restoring lost or unreachable cryptocurrency by using sophisticated blockchain analytics and investigative techniques. They provide frank assessments and trustworthy assistance to people and companies affected by cryptocurrency losses, and they are renowned for their ethical standards and open communication. Learn More About iFORCE HACKER RECOVERY Website: ht tps :// iforcehackers. co m WhatsApp: +1 240-803-3706 Email: iforcehk @ consultant. c om

3 months

[PATCH 2/8] dma-buf: detach fence ops on signal v2

by Christian König

When neither a release nor a wait backend ops is specified it is possible to let the dma_fence live on independently of the module who issued it. This makes it possible to unload drivers and only wait for all their fences to signal. v2: fix typo in comment Signed-off-by: Christian König <christian.koenig(a)amd.com> Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin(a)igalia.com> Reviewed-by: Philipp Stanner <phasta(a)kernel.org> Reviewed-by: Boris Brezillon <boris.brezillon(a)collabora.com> --- drivers/dma-buf/dma-fence.c | 16 ++++++++++++---- include/linux/dma-fence.h | 4 ++-- 2 files changed, 14 insertions(+), 6 deletions(-) diff --git a/drivers/dma-buf/dma-fence.c b/drivers/dma-buf/dma-fence.c index d3c4e23bf297..ae77f900c267 100644 --- a/drivers/dma-buf/dma-fence.c +++ b/drivers/dma-buf/dma-fence.c @@ -371,6 +371,14 @@ void dma_fence_signal_timestamp_locked(struct dma_fence *fence, &fence->flags))) return; + /* + * When neither a release nor a wait operation is specified set the ops + * pointer to NULL to allow the fence structure to become independent + * from who originally issued it. + */ + if (!fence->ops->release && !fence->ops->wait) + RCU_INIT_POINTER(fence->ops, NULL); + /* Stash the cb_list before replacing it with the timestamp */ list_replace(&fence->cb_list, &cb_list); @@ -537,7 +545,7 @@ dma_fence_wait_timeout(struct dma_fence *fence, bool intr, signed long timeout) rcu_read_lock(); ops = rcu_dereference(fence->ops); trace_dma_fence_wait_start(fence); - if (ops->wait) { + if (ops && ops->wait) { /* * Implementing the wait ops is deprecated and not supported for * issuers of fences who need their lifetime to be independent @@ -603,7 +611,7 @@ void dma_fence_release(struct kref *kref) } ops = rcu_dereference(fence->ops); - if (ops->release) + if (ops && ops->release) ops->release(fence); else dma_fence_free(fence); @@ -639,7 +647,7 @@ static bool __dma_fence_enable_signaling(struct dma_fence *fence) rcu_read_lock(); ops = rcu_dereference(fence->ops); - if (!was_set && ops->enable_signaling) { + if (!was_set && ops && ops->enable_signaling) { trace_dma_fence_enable_signal(fence); if (!ops->enable_signaling(fence)) { @@ -1025,7 +1033,7 @@ void dma_fence_set_deadline(struct dma_fence *fence, ktime_t deadline) rcu_read_lock(); ops = rcu_dereference(fence->ops); - if (ops->set_deadline && !dma_fence_is_signaled(fence)) + if (ops && ops->set_deadline && !dma_fence_is_signaled(fence)) ops->set_deadline(fence, deadline); rcu_read_unlock(); } diff --git a/include/linux/dma-fence.h b/include/linux/dma-fence.h index 9d8a4ebe8bf7..80db7ede91de 100644 --- a/include/linux/dma-fence.h +++ b/include/linux/dma-fence.h @@ -472,7 +472,7 @@ dma_fence_is_signaled_locked(struct dma_fence *fence) rcu_read_lock(); ops = rcu_dereference(fence->ops); - if (ops->signaled && ops->signaled(fence)) { + if (ops && ops->signaled && ops->signaled(fence)) { rcu_read_unlock(); dma_fence_signal_locked(fence); return true; @@ -508,7 +508,7 @@ dma_fence_is_signaled(struct dma_fence *fence) rcu_read_lock(); ops = rcu_dereference(fence->ops); - if (ops->signaled && ops->signaled(fence)) { + if (ops && ops->signaled && ops->signaled(fence)) { rcu_read_unlock(); dma_fence_signal(fence); return true; -- 2.43.0

3 months

[PATCH 1/8] dma-buf: protected fence ops by RCU v7

by Christian König

The fence ops of a dma_fence currently need to life as long as the dma_fence is alive. This means that the module which originally issued a dma_fence can't unload unless all fences are freed up. As first step to solve this issue protect the fence ops by RCU. While it is counter intuitive to protect a constant function pointer table by RCU it allows modules to wait for an RCU grace period before they unload, to make sure that nobody is executing their functions any more. This patch has not much functional change, but only adds the RCU handling for the static checker to test. v2: make one the now duplicated lockdep warnings a comment instead. v3: Add more documentation to ->wait and ->release callback. v4: fix typo in documentation v5: rebased on drm-tip v6: improve code comments v7: improve commit message and code comments Signed-off-by: Christian König <christian.koenig(a)amd.com> Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin(a)igalia.com> Reviewed-by: Boris Brezillon <boris.brezillon(a)collabora.com> --- drivers/dma-buf/dma-fence.c | 71 +++++++++++++++++++++++++------------ include/linux/dma-fence.h | 29 +++++++++++++-- 2 files changed, 75 insertions(+), 25 deletions(-) diff --git a/drivers/dma-buf/dma-fence.c b/drivers/dma-buf/dma-fence.c index e05beae6e407..d3c4e23bf297 100644 --- a/drivers/dma-buf/dma-fence.c +++ b/drivers/dma-buf/dma-fence.c @@ -522,6 +522,7 @@ EXPORT_SYMBOL(dma_fence_signal); signed long dma_fence_wait_timeout(struct dma_fence *fence, bool intr, signed long timeout) { + const struct dma_fence_ops *ops; signed long ret; if (WARN_ON(timeout < 0)) @@ -533,15 +534,22 @@ dma_fence_wait_timeout(struct dma_fence *fence, bool intr, signed long timeout) dma_fence_enable_sw_signaling(fence); - if (trace_dma_fence_wait_start_enabled()) { - rcu_read_lock(); - trace_dma_fence_wait_start(fence); + rcu_read_lock(); + ops = rcu_dereference(fence->ops); + trace_dma_fence_wait_start(fence); + if (ops->wait) { + /* + * Implementing the wait ops is deprecated and not supported for + * issuers of fences who need their lifetime to be independent + * of their module after they signal, so it is ok to use the + * ops outside the RCU protected section. + */ + rcu_read_unlock(); + ret = ops->wait(fence, intr, timeout); + } else { rcu_read_unlock(); - } - if (fence->ops->wait) - ret = fence->ops->wait(fence, intr, timeout); - else ret = dma_fence_default_wait(fence, intr, timeout); + } if (trace_dma_fence_wait_end_enabled()) { rcu_read_lock(); trace_dma_fence_wait_end(fence); @@ -562,6 +570,7 @@ void dma_fence_release(struct kref *kref) { struct dma_fence *fence = container_of(kref, struct dma_fence, refcount); + const struct dma_fence_ops *ops; rcu_read_lock(); trace_dma_fence_destroy(fence); @@ -593,12 +602,12 @@ void dma_fence_release(struct kref *kref) spin_unlock_irqrestore(fence->lock, flags); } - rcu_read_unlock(); - - if (fence->ops->release) - fence->ops->release(fence); + ops = rcu_dereference(fence->ops); + if (ops->release) + ops->release(fence); else dma_fence_free(fence); + rcu_read_unlock(); } EXPORT_SYMBOL(dma_fence_release); @@ -617,6 +626,7 @@ EXPORT_SYMBOL(dma_fence_free); static bool __dma_fence_enable_signaling(struct dma_fence *fence) { + const struct dma_fence_ops *ops; bool was_set; lockdep_assert_held(fence->lock); @@ -627,14 +637,18 @@ static bool __dma_fence_enable_signaling(struct dma_fence *fence) if (dma_fence_test_signaled_flag(fence)) return false; - if (!was_set && fence->ops->enable_signaling) { + rcu_read_lock(); + ops = rcu_dereference(fence->ops); + if (!was_set && ops->enable_signaling) { trace_dma_fence_enable_signal(fence); - if (!fence->ops->enable_signaling(fence)) { + if (!ops->enable_signaling(fence)) { + rcu_read_unlock(); dma_fence_signal_locked(fence); return false; } } + rcu_read_unlock(); return true; } @@ -1007,8 +1021,13 @@ EXPORT_SYMBOL(dma_fence_wait_any_timeout); */ void dma_fence_set_deadline(struct dma_fence *fence, ktime_t deadline) { - if (fence->ops->set_deadline && !dma_fence_is_signaled(fence)) - fence->ops->set_deadline(fence, deadline); + const struct dma_fence_ops *ops; + + rcu_read_lock(); + ops = rcu_dereference(fence->ops); + if (ops->set_deadline && !dma_fence_is_signaled(fence)) + ops->set_deadline(fence, deadline); + rcu_read_unlock(); } EXPORT_SYMBOL(dma_fence_set_deadline); @@ -1049,7 +1068,13 @@ __dma_fence_init(struct dma_fence *fence, const struct dma_fence_ops *ops, BUG_ON(!ops || !ops->get_driver_name || !ops->get_timeline_name); kref_init(&fence->refcount); - fence->ops = ops; + /* + * While it is counter intuitive to protect a constant function pointer + * table by RCU it allows modules to wait for an RCU grace period + * before they unload, to make sure that nobody is executing their + * functions any more. + */ + RCU_INIT_POINTER(fence->ops, ops); INIT_LIST_HEAD(&fence->cb_list); fence->lock = lock; fence->context = context; @@ -1129,11 +1154,12 @@ EXPORT_SYMBOL(dma_fence_init64); */ const char __rcu *dma_fence_driver_name(struct dma_fence *fence) { - RCU_LOCKDEP_WARN(!rcu_read_lock_held(), - "RCU protection is required for safe access to returned string"); + const struct dma_fence_ops *ops; + /* RCU protection is required for safe access to returned string */ + ops = rcu_dereference(fence->ops); if (!dma_fence_test_signaled_flag(fence)) - return (const char __rcu *)fence->ops->get_driver_name(fence); + return (const char __rcu *)ops->get_driver_name(fence); else return (const char __rcu *)"detached-driver"; } @@ -1161,11 +1187,12 @@ EXPORT_SYMBOL(dma_fence_driver_name); */ const char __rcu *dma_fence_timeline_name(struct dma_fence *fence) { - RCU_LOCKDEP_WARN(!rcu_read_lock_held(), - "RCU protection is required for safe access to returned string"); + const struct dma_fence_ops *ops; + /* RCU protection is required for safe access to returned string */ + ops = rcu_dereference(fence->ops); if (!dma_fence_test_signaled_flag(fence)) - return (const char __rcu *)fence->ops->get_driver_name(fence); + return (const char __rcu *)ops->get_driver_name(fence); else return (const char __rcu *)"signaled-timeline"; } diff --git a/include/linux/dma-fence.h b/include/linux/dma-fence.h index 9c4d25289239..9d8a4ebe8bf7 100644 --- a/include/linux/dma-fence.h +++ b/include/linux/dma-fence.h @@ -67,7 +67,7 @@ struct seq_file; */ struct dma_fence { spinlock_t *lock; - const struct dma_fence_ops *ops; + const struct dma_fence_ops __rcu *ops; /* * We clear the callback list on kref_put so that by the time we * release the fence it is unused. No one should be adding to the @@ -220,6 +220,10 @@ struct dma_fence_ops { * timed out. Can also return other error values on custom implementations, * which should be treated as if the fence is signaled. For example a hardware * lockup could be reported like that. + * + * Implementing this callback prevents the fence from detaching after + * signaling and so it is necessary for the module providing the + * dma_fence_ops to stay loaded as long as the dma_fence exists. */ signed long (*wait)(struct dma_fence *fence, bool intr, signed long timeout); @@ -231,6 +235,13 @@ struct dma_fence_ops { * Can be called from irq context. This callback is optional. If it is * NULL, then dma_fence_free() is instead called as the default * implementation. + * + * Implementing this callback prevents the fence from detaching after + * signaling and so it is necessary for the module providing the + * dma_fence_ops to stay loaded as long as the dma_fence exists. + * + * If the callback is implemented the memory backing the dma_fence + * object must be freed RCU safe. */ void (*release)(struct dma_fence *fence); @@ -454,13 +465,19 @@ dma_fence_test_signaled_flag(struct dma_fence *fence) static inline bool dma_fence_is_signaled_locked(struct dma_fence *fence) { + const struct dma_fence_ops *ops; + if (dma_fence_test_signaled_flag(fence)) return true; - if (fence->ops->signaled && fence->ops->signaled(fence)) { + rcu_read_lock(); + ops = rcu_dereference(fence->ops); + if (ops->signaled && ops->signaled(fence)) { + rcu_read_unlock(); dma_fence_signal_locked(fence); return true; } + rcu_read_unlock(); return false; } @@ -484,13 +501,19 @@ dma_fence_is_signaled_locked(struct dma_fence *fence) static inline bool dma_fence_is_signaled(struct dma_fence *fence) { + const struct dma_fence_ops *ops; + if (dma_fence_test_signaled_flag(fence)) return true; - if (fence->ops->signaled && fence->ops->signaled(fence)) { + rcu_read_lock(); + ops = rcu_dereference(fence->ops); + if (ops->signaled && ops->signaled(fence)) { + rcu_read_unlock(); dma_fence_signal(fence); return true; } + rcu_read_unlock(); return false; } -- 2.43.0

3 months