From e8dd273d199f5bbe295a8e3d8b777c5505b6b2e1 Mon Sep 17 00:00:00 2001 From: Salah Triki Date: Thu, 17 Sep 2026 14:00:52 +0100 Subject: iio: proximity: isl29501: Fix return type of isl29501_register_write isl29501_register_write() was returning a u32 instead of an int. Since the function returns negative error codes (such as -ERANGE or return values from i2c_smbus_write_byte_data()), returning an unsigned integer type prevents callers from correctly checking for negative error conditions. Fix this by changing the function return type from u32 to int. This was found through manual code review. Fixes: 1c28799257bc ("iio: light: isl29501: Add support for the ISL29501 ToF sensor.") Signed-off-by: Salah Triki Reviewed-by: Joshua Crofts Cc: stable@vger.kernel.org Signed-off-by: Jonathan Cameron --- include/drm/spsc_queue.h | 124 +++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 124 insertions(+) create mode 100644 include/drm/spsc_queue.h (limited to 'include/drm/spsc_queue.h') diff --git a/include/drm/spsc_queue.h b/include/drm/spsc_queue.h new file mode 100644 index 000000000..ee9df8cc6 --- /dev/null +++ b/include/drm/spsc_queue.h @@ -0,0 +1,124 @@ +/* + * Copyright 2017 Advanced Micro Devices, Inc. + * + * Permission is hereby granted, free of charge, to any person obtaining a + * copy of this software and associated documentation files (the "Software"), + * to deal in the Software without restriction, including without limitation + * the rights to use, copy, modify, merge, publish, distribute, sublicense, + * and/or sell copies of the Software, and to permit persons to whom the + * Software is furnished to do so, subject to the following conditions: + * + * The above copyright notice and this permission notice shall be included in + * all copies or substantial portions of the Software. + * + * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR + * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, + * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL + * THE COPYRIGHT HOLDER(S) OR AUTHOR(S) BE LIABLE FOR ANY CLAIM, DAMAGES OR + * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, + * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR + * OTHER DEALINGS IN THE SOFTWARE. + * + */ + +#ifndef DRM_SCHEDULER_SPSC_QUEUE_H_ +#define DRM_SCHEDULER_SPSC_QUEUE_H_ + +#include +#include + +/** SPSC lockless queue */ + +struct spsc_node { + + /* Stores spsc_node* */ + struct spsc_node *next; +}; + +struct spsc_queue { + + struct spsc_node *head; + + /* atomic pointer to struct spsc_node* */ + atomic_long_t tail; + + atomic_t job_count; +}; + +static inline void spsc_queue_init(struct spsc_queue *queue) +{ + queue->head = NULL; + atomic_long_set(&queue->tail, (long)&queue->head); + atomic_set(&queue->job_count, 0); +} + +static inline struct spsc_node *spsc_queue_peek(struct spsc_queue *queue) +{ + return queue->head; +} + +static inline int spsc_queue_count(struct spsc_queue *queue) +{ + return atomic_read(&queue->job_count); +} + +static inline bool spsc_queue_push(struct spsc_queue *queue, struct spsc_node *node) +{ + struct spsc_node **tail; + + node->next = NULL; + + preempt_disable(); + + atomic_inc(&queue->job_count); + smp_mb__after_atomic(); + + tail = (struct spsc_node **)atomic_long_xchg(&queue->tail, (long)&node->next); + WRITE_ONCE(*tail, node); + + /* + * In case of first element verify new node will be visible to the consumer + * thread when we ping the kernel thread that there is new work to do. + */ + smp_wmb(); + + preempt_enable(); + + return tail == &queue->head; +} + + +static inline struct spsc_node *spsc_queue_pop(struct spsc_queue *queue) +{ + struct spsc_node *next, *node; + + /* Verify reading from memory and not the cache */ + smp_rmb(); + + node = READ_ONCE(queue->head); + + if (!node) + return NULL; + + next = READ_ONCE(node->next); + WRITE_ONCE(queue->head, next); + + if (unlikely(!next)) { + /* slowpath for the last element in the queue */ + + if (atomic_long_cmpxchg(&queue->tail, + (long)&node->next, (long) &queue->head) != (long)&node->next) { + /* Updating tail failed wait for new next to appear */ + do { + smp_rmb(); + } while (unlikely(!(queue->head = READ_ONCE(node->next)))); + } + } + + atomic_dec(&queue->job_count); + return node; +} + + + +#endif /* DRM_SCHEDULER_SPSC_QUEUE_H_ */ -- cgit v1.3.1