mirror of https://github.com/hak5/openwrt.git
193 lines
6.0 KiB
Diff
193 lines
6.0 KiB
Diff
From 965475a1620ba1c4f19d6585925a40e3c749d7d1 Mon Sep 17 00:00:00 2001
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From: Phil Elwell <phil@raspberrypi.org>
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Date: Mon, 20 Jun 2016 13:51:44 +0100
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Subject: [PATCH] vchiq_arm: Avoid use of mutex in add_completion
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Claiming the completion_mutex within add_completion did prevent some
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messages appearing twice, but provokes a deadlock caused by vcsm using
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vchiq within a page fault handler.
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Revert the use of completion_mutex, and instead fix the original
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problem using more memory barriers.
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Signed-off-by: Phil Elwell <phil@raspberrypi.org>
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---
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.../vc04_services/interface/vchiq_arm/vchiq_arm.c | 55 +++++++++++-----------
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.../vc04_services/interface/vchiq_arm/vchiq_core.c | 14 ++++--
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2 files changed, 37 insertions(+), 32 deletions(-)
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--- a/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_arm.c
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+++ b/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_arm.c
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@@ -64,10 +64,10 @@
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#define VCHIQ_MINOR 0
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/* Some per-instance constants */
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-#define MAX_COMPLETIONS 16
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+#define MAX_COMPLETIONS 128
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#define MAX_SERVICES 64
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#define MAX_ELEMENTS 8
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-#define MSG_QUEUE_SIZE 64
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+#define MSG_QUEUE_SIZE 128
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#define KEEPALIVE_VER 1
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#define KEEPALIVE_VER_MIN KEEPALIVE_VER
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@@ -208,28 +208,24 @@ add_completion(VCHIQ_INSTANCE_T instance
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void *bulk_userdata)
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{
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VCHIQ_COMPLETION_DATA_T *completion;
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+ int insert;
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DEBUG_INITIALISE(g_state.local)
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- mutex_lock(&instance->completion_mutex);
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-
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- while (instance->completion_insert ==
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- (instance->completion_remove + MAX_COMPLETIONS)) {
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+ insert = instance->completion_insert;
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+ while ((insert - instance->completion_remove) >= MAX_COMPLETIONS) {
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/* Out of space - wait for the client */
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DEBUG_TRACE(SERVICE_CALLBACK_LINE);
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vchiq_log_trace(vchiq_arm_log_level,
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"add_completion - completion queue full");
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DEBUG_COUNT(COMPLETION_QUEUE_FULL_COUNT);
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- mutex_unlock(&instance->completion_mutex);
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if (down_interruptible(&instance->remove_event) != 0) {
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vchiq_log_info(vchiq_arm_log_level,
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"service_callback interrupted");
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return VCHIQ_RETRY;
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}
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- mutex_lock(&instance->completion_mutex);
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if (instance->closing) {
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- mutex_unlock(&instance->completion_mutex);
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vchiq_log_info(vchiq_arm_log_level,
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"service_callback closing");
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return VCHIQ_SUCCESS;
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@@ -237,9 +233,7 @@ add_completion(VCHIQ_INSTANCE_T instance
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DEBUG_TRACE(SERVICE_CALLBACK_LINE);
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}
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- completion =
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- &instance->completions[instance->completion_insert &
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- (MAX_COMPLETIONS - 1)];
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+ completion = &instance->completions[insert & (MAX_COMPLETIONS - 1)];
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completion->header = header;
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completion->reason = reason;
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@@ -260,12 +254,9 @@ add_completion(VCHIQ_INSTANCE_T instance
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wmb();
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if (reason == VCHIQ_MESSAGE_AVAILABLE)
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- user_service->message_available_pos =
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- instance->completion_insert;
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-
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- instance->completion_insert++;
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+ user_service->message_available_pos = insert;
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- mutex_unlock(&instance->completion_mutex);
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+ instance->completion_insert = ++insert;
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up(&instance->insert_event);
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@@ -795,6 +786,7 @@ vchiq_ioctl(struct file *file, unsigned
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instance->completion_insert)
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&& !instance->closing) {
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int rc;
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+
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DEBUG_TRACE(AWAIT_COMPLETION_LINE);
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mutex_unlock(&instance->completion_mutex);
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rc = down_interruptible(&instance->insert_event);
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@@ -809,24 +801,29 @@ vchiq_ioctl(struct file *file, unsigned
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}
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DEBUG_TRACE(AWAIT_COMPLETION_LINE);
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- /* A read memory barrier is needed to stop prefetch of a stale
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- ** completion record
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- */
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- rmb();
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-
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if (ret == 0) {
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int msgbufcount = args.msgbufcount;
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+ int remove;
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+
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+ remove = instance->completion_remove;
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+
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for (ret = 0; ret < args.count; ret++) {
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VCHIQ_COMPLETION_DATA_T *completion;
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VCHIQ_SERVICE_T *service;
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USER_SERVICE_T *user_service;
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VCHIQ_HEADER_T *header;
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- if (instance->completion_remove ==
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- instance->completion_insert)
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+
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+ if (remove == instance->completion_insert)
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break;
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+
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completion = &instance->completions[
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- instance->completion_remove &
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- (MAX_COMPLETIONS - 1)];
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+ remove & (MAX_COMPLETIONS - 1)];
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+
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+
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+ /* A read memory barrier is needed to prevent
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+ ** the prefetch of a stale completion record
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+ */
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+ rmb();
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service = completion->service_userdata;
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user_service = service->base.userdata;
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@@ -903,7 +900,11 @@ vchiq_ioctl(struct file *file, unsigned
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break;
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}
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- instance->completion_remove++;
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+ /* Ensure that the above copy has completed
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+ ** before advancing the remove pointer. */
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+ mb();
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+
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+ instance->completion_remove = ++remove;
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}
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if (msgbufcount != args.msgbufcount) {
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--- a/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_core.c
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+++ b/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_core.c
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@@ -610,15 +610,15 @@ process_free_queue(VCHIQ_STATE_T *state)
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BITSET_T service_found[BITSET_SIZE(VCHIQ_MAX_SERVICES)];
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int slot_queue_available;
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- /* Use a read memory barrier to ensure that any state that may have
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- ** been modified by another thread is not masked by stale prefetched
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- ** values. */
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- rmb();
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-
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/* Find slots which have been freed by the other side, and return them
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** to the available queue. */
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slot_queue_available = state->slot_queue_available;
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+ /* Use a memory barrier to ensure that any state that may have been
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+ ** modified by another thread is not masked by stale prefetched
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+ ** values. */
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+ mb();
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+
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while (slot_queue_available != local->slot_queue_recycle) {
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unsigned int pos;
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int slot_index = local->slot_queue[slot_queue_available++ &
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@@ -626,6 +626,8 @@ process_free_queue(VCHIQ_STATE_T *state)
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char *data = (char *)SLOT_DATA_FROM_INDEX(state, slot_index);
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int data_found = 0;
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+ rmb();
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+
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vchiq_log_trace(vchiq_core_log_level, "%d: pfq %d=%x %x %x",
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state->id, slot_index, (unsigned int)data,
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local->slot_queue_recycle, slot_queue_available);
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@@ -741,6 +743,8 @@ process_free_queue(VCHIQ_STATE_T *state)
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up(&state->data_quota_event);
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}
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+ mb();
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+
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state->slot_queue_available = slot_queue_available;
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up(&state->slot_available_event);
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}
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