This is a note to let you know that I've just added the patch titled
dmaengine: dmatest: move callback wait queue to thread context
to the 4.4-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git%3Ba=su...
The filename of the patch is: dmaengine-dmatest-move-callback-wait-queue-to-thread-context.patch and it can be found in the queue-4.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree, please let stable@vger.kernel.org know about it.
From 6f6a23a213be51728502b88741ba6a10cda2441d Mon Sep 17 00:00:00 2001
From: Adam Wallis awallis@codeaurora.org Date: Mon, 27 Nov 2017 10:45:01 -0500 Subject: dmaengine: dmatest: move callback wait queue to thread context
From: Adam Wallis awallis@codeaurora.org
commit 6f6a23a213be51728502b88741ba6a10cda2441d upstream.
Commit adfa543e7314 ("dmatest: don't use set_freezable_with_signal()") introduced a bug (that is in fact documented by the patch commit text) that leaves behind a dangling pointer. Since the done_wait structure is allocated on the stack, future invocations to the DMATEST can produce undesirable results (e.g., corrupted spinlocks).
Commit a9df21e34b42 ("dmaengine: dmatest: warn user when dma test times out") attempted to WARN the user that the stack was likely corrupted but did not fix the actual issue.
This patch fixes the issue by pushing the wait queue and callback structs into the the thread structure. If a failure occurs due to time, dmaengine_terminate_all will force the callback to safely call wake_up_all() without possibility of using a freed pointer.
Bug: https://bugzilla.kernel.org/show_bug.cgi?id=197605 Fixes: adfa543e7314 ("dmatest: don't use set_freezable_with_signal()") Reviewed-by: Sinan Kaya okaya@codeaurora.org Suggested-by: Shunyong Yang shunyong.yang@hxt-semitech.com Signed-off-by: Adam Wallis awallis@codeaurora.org Signed-off-by: Vinod Koul vinod.koul@intel.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- drivers/dma/dmatest.c | 55 ++++++++++++++++++++++++++++---------------------- 1 file changed, 31 insertions(+), 24 deletions(-)
--- a/drivers/dma/dmatest.c +++ b/drivers/dma/dmatest.c @@ -148,6 +148,12 @@ MODULE_PARM_DESC(run, "Run the test (def #define PATTERN_OVERWRITE 0x20 #define PATTERN_COUNT_MASK 0x1f
+/* poor man's completion - we want to use wait_event_freezable() on it */ +struct dmatest_done { + bool done; + wait_queue_head_t *wait; +}; + struct dmatest_thread { struct list_head node; struct dmatest_info *info; @@ -156,6 +162,8 @@ struct dmatest_thread { u8 **srcs; u8 **dsts; enum dma_transaction_type type; + wait_queue_head_t done_wait; + struct dmatest_done test_done; bool done; };
@@ -316,18 +324,25 @@ static unsigned int dmatest_verify(u8 ** return error_count; }
-/* poor man's completion - we want to use wait_event_freezable() on it */ -struct dmatest_done { - bool done; - wait_queue_head_t *wait; -};
static void dmatest_callback(void *arg) { struct dmatest_done *done = arg; - - done->done = true; - wake_up_all(done->wait); + struct dmatest_thread *thread = + container_of(arg, struct dmatest_thread, done_wait); + if (!thread->done) { + done->done = true; + wake_up_all(done->wait); + } else { + /* + * If thread->done, it means that this callback occurred + * after the parent thread has cleaned up. This can + * happen in the case that driver doesn't implement + * the terminate_all() functionality and a dma operation + * did not occur within the timeout period + */ + WARN(1, "dmatest: Kernel memory may be corrupted!!\n"); + } }
static unsigned int min_odd(unsigned int x, unsigned int y) @@ -398,9 +413,8 @@ static unsigned long long dmatest_KBs(s6 */ static int dmatest_func(void *data) { - DECLARE_WAIT_QUEUE_HEAD_ONSTACK(done_wait); struct dmatest_thread *thread = data; - struct dmatest_done done = { .wait = &done_wait }; + struct dmatest_done *done = &thread->test_done; struct dmatest_info *info; struct dmatest_params *params; struct dma_chan *chan; @@ -605,9 +619,9 @@ static int dmatest_func(void *data) continue; }
- done.done = false; + done->done = false; tx->callback = dmatest_callback; - tx->callback_param = &done; + tx->callback_param = done; cookie = tx->tx_submit(tx);
if (dma_submit_error(cookie)) { @@ -620,21 +634,12 @@ static int dmatest_func(void *data) } dma_async_issue_pending(chan);
- wait_event_freezable_timeout(done_wait, done.done, + wait_event_freezable_timeout(thread->done_wait, done->done, msecs_to_jiffies(params->timeout));
status = dma_async_is_tx_complete(chan, cookie, NULL, NULL);
- if (!done.done) { - /* - * We're leaving the timed out dma operation with - * dangling pointer to done_wait. To make this - * correct, we'll need to allocate wait_done for - * each test iteration and perform "who's gonna - * free it this time?" dancing. For now, just - * leave it dangling. - */ - WARN(1, "dmatest: Kernel stack may be corrupted!!\n"); + if (!done->done) { dmaengine_unmap_put(um); result("test timed out", total_tests, src_off, dst_off, len, 0); @@ -708,7 +713,7 @@ err_thread_type: dmatest_KBs(runtime, total_len), ret);
/* terminate all transfers on specified channels */ - if (ret) + if (ret || failed_tests) dmaengine_terminate_all(chan);
thread->done = true; @@ -766,6 +771,8 @@ static int dmatest_add_threads(struct dm thread->info = info; thread->chan = dtc->chan; thread->type = type; + thread->test_done.wait = &thread->done_wait; + init_waitqueue_head(&thread->done_wait); smp_wmb(); thread->task = kthread_create(dmatest_func, thread, "%s-%s%u", dma_chan_name(chan), op, i);
Patches currently in stable-queue which might be from awallis@codeaurora.org are
queue-4.4/dmaengine-dmatest-move-callback-wait-queue-to-thread-context.patch