diff options
Diffstat (limited to 'target/linux/brcm2708/patches-4.4/0426-vchiq_arm-Avoid-use-of-mutex-in-add_completion.patch')
| -rw-r--r-- | target/linux/brcm2708/patches-4.4/0426-vchiq_arm-Avoid-use-of-mutex-in-add_completion.patch | 192 |
1 files changed, 0 insertions, 192 deletions
diff --git a/target/linux/brcm2708/patches-4.4/0426-vchiq_arm-Avoid-use-of-mutex-in-add_completion.patch b/target/linux/brcm2708/patches-4.4/0426-vchiq_arm-Avoid-use-of-mutex-in-add_completion.patch deleted file mode 100644 index d2edccc1b3..0000000000 --- a/target/linux/brcm2708/patches-4.4/0426-vchiq_arm-Avoid-use-of-mutex-in-add_completion.patch +++ /dev/null @@ -1,192 +0,0 @@ -From c1aad7829f0bb4f13b6a61879361f2405eed2a9b Mon Sep 17 00:00:00 2001 -From: Phil Elwell <phil@raspberrypi.org> -Date: Mon, 20 Jun 2016 13:51:44 +0100 -Subject: [PATCH] vchiq_arm: Avoid use of mutex in add_completion - -Claiming the completion_mutex within add_completion did prevent some -messages appearing twice, but provokes a deadlock caused by vcsm using -vchiq within a page fault handler. - -Revert the use of completion_mutex, and instead fix the original -problem using more memory barriers. - -Signed-off-by: Phil Elwell <phil@raspberrypi.org> ---- - .../vc04_services/interface/vchiq_arm/vchiq_arm.c | 55 +++++++++++----------- - .../vc04_services/interface/vchiq_arm/vchiq_core.c | 14 ++++-- - 2 files changed, 37 insertions(+), 32 deletions(-) - ---- a/drivers/misc/vc04_services/interface/vchiq_arm/vchiq_arm.c -+++ b/drivers/misc/vc04_services/interface/vchiq_arm/vchiq_arm.c -@@ -64,10 +64,10 @@ - #define VCHIQ_MINOR 0 - - /* Some per-instance constants */ --#define MAX_COMPLETIONS 16 -+#define MAX_COMPLETIONS 128 - #define MAX_SERVICES 64 - #define MAX_ELEMENTS 8 --#define MSG_QUEUE_SIZE 64 -+#define MSG_QUEUE_SIZE 128 - - #define KEEPALIVE_VER 1 - #define KEEPALIVE_VER_MIN KEEPALIVE_VER -@@ -208,28 +208,24 @@ add_completion(VCHIQ_INSTANCE_T instance - void *bulk_userdata) - { - VCHIQ_COMPLETION_DATA_T *completion; -+ int insert; - DEBUG_INITIALISE(g_state.local) - -- mutex_lock(&instance->completion_mutex); -- -- while (instance->completion_insert == -- (instance->completion_remove + MAX_COMPLETIONS)) { -+ insert = instance->completion_insert; -+ while ((insert - instance->completion_remove) >= MAX_COMPLETIONS) { - /* Out of space - wait for the client */ - DEBUG_TRACE(SERVICE_CALLBACK_LINE); - vchiq_log_trace(vchiq_arm_log_level, - "add_completion - completion queue full"); - DEBUG_COUNT(COMPLETION_QUEUE_FULL_COUNT); - -- mutex_unlock(&instance->completion_mutex); - if (down_interruptible(&instance->remove_event) != 0) { - vchiq_log_info(vchiq_arm_log_level, - "service_callback interrupted"); - return VCHIQ_RETRY; - } - -- mutex_lock(&instance->completion_mutex); - if (instance->closing) { -- mutex_unlock(&instance->completion_mutex); - vchiq_log_info(vchiq_arm_log_level, - "service_callback closing"); - return VCHIQ_SUCCESS; -@@ -237,9 +233,7 @@ add_completion(VCHIQ_INSTANCE_T instance - DEBUG_TRACE(SERVICE_CALLBACK_LINE); - } - -- completion = -- &instance->completions[instance->completion_insert & -- (MAX_COMPLETIONS - 1)]; -+ completion = &instance->completions[insert & (MAX_COMPLETIONS - 1)]; - - completion->header = header; - completion->reason = reason; -@@ -260,12 +254,9 @@ add_completion(VCHIQ_INSTANCE_T instance - wmb(); - - if (reason == VCHIQ_MESSAGE_AVAILABLE) -- user_service->message_available_pos = -- instance->completion_insert; -- -- instance->completion_insert++; -+ user_service->message_available_pos = insert; - -- mutex_unlock(&instance->completion_mutex); -+ instance->completion_insert = ++insert; - - up(&instance->insert_event); - -@@ -795,6 +786,7 @@ vchiq_ioctl(struct file *file, unsigned - instance->completion_insert) - && !instance->closing) { - int rc; -+ - DEBUG_TRACE(AWAIT_COMPLETION_LINE); - mutex_unlock(&instance->completion_mutex); - rc = down_interruptible(&instance->insert_event); -@@ -809,24 +801,29 @@ vchiq_ioctl(struct file *file, unsigned - } - DEBUG_TRACE(AWAIT_COMPLETION_LINE); - -- /* A read memory barrier is needed to stop prefetch of a stale -- ** completion record -- */ -- rmb(); -- - if (ret == 0) { - int msgbufcount = args.msgbufcount; -+ int remove; -+ -+ remove = instance->completion_remove; -+ - for (ret = 0; ret < args.count; ret++) { - VCHIQ_COMPLETION_DATA_T *completion; - VCHIQ_SERVICE_T *service; - USER_SERVICE_T *user_service; - VCHIQ_HEADER_T *header; -- if (instance->completion_remove == -- instance->completion_insert) -+ -+ if (remove == instance->completion_insert) - break; -+ - completion = &instance->completions[ -- instance->completion_remove & -- (MAX_COMPLETIONS - 1)]; -+ remove & (MAX_COMPLETIONS - 1)]; -+ -+ -+ /* A read memory barrier is needed to prevent -+ ** the prefetch of a stale completion record -+ */ -+ rmb(); - - service = completion->service_userdata; - user_service = service->base.userdata; -@@ -903,7 +900,11 @@ vchiq_ioctl(struct file *file, unsigned - break; - } - -- instance->completion_remove++; -+ /* Ensure that the above copy has completed -+ ** before advancing the remove pointer. */ -+ mb(); -+ -+ instance->completion_remove = ++remove; - } - - if (msgbufcount != args.msgbufcount) { ---- a/drivers/misc/vc04_services/interface/vchiq_arm/vchiq_core.c -+++ b/drivers/misc/vc04_services/interface/vchiq_arm/vchiq_core.c -@@ -610,15 +610,15 @@ process_free_queue(VCHIQ_STATE_T *state) - BITSET_T service_found[BITSET_SIZE(VCHIQ_MAX_SERVICES)]; - int slot_queue_available; - -- /* Use a read memory barrier to ensure that any state that may have -- ** been modified by another thread is not masked by stale prefetched -- ** values. */ -- rmb(); -- - /* Find slots which have been freed by the other side, and return them - ** to the available queue. */ - slot_queue_available = state->slot_queue_available; - -+ /* Use a memory barrier to ensure that any state that may have been -+ ** modified by another thread is not masked by stale prefetched -+ ** values. */ -+ mb(); -+ - while (slot_queue_available != local->slot_queue_recycle) { - unsigned int pos; - int slot_index = local->slot_queue[slot_queue_available++ & -@@ -626,6 +626,8 @@ process_free_queue(VCHIQ_STATE_T *state) - char *data = (char *)SLOT_DATA_FROM_INDEX(state, slot_index); - int data_found = 0; - -+ rmb(); -+ - vchiq_log_trace(vchiq_core_log_level, "%d: pfq %d=%x %x %x", - state->id, slot_index, (unsigned int)data, - local->slot_queue_recycle, slot_queue_available); -@@ -741,6 +743,8 @@ process_free_queue(VCHIQ_STATE_T *state) - up(&state->data_quota_event); - } - -+ mb(); -+ - state->slot_queue_available = slot_queue_available; - up(&state->slot_available_event); - } |