ntb_perf: Improve thread handling to increase robustness
This commit accomplishes a few things: 1) Properly prevent multiple sets of threads from running at once using a mutex. Lots of race issues existed with the thread_cleanup. 2) The mutex allows us to ensure that threads are finished before tearing down the device or module. 3) Don't use kthread_stop when the threads can exit by themselves, as this is counter-indicated by the kthread_create documentation. Threads now wait for kthread_stop to occur. 4) Writing to the run file now blocks until the threads are complete. The test can then be safely interrupted by a SIGINT. Also, while I was at it: 5) debugfs_run_write shouldn't return 0 in the early check cases as this could cause debugfs_run_write to loop undesirably. Signed-off-by: Logan Gunthorpe <logang@deltatee.com> Acked-by: Dave Jiang <dave.jiang@intel.com> Signed-off-by: Jon Mason <jdmason@kudzu.us>
This commit is contained in:
Logan Gunthorpe
Jon Mason
parent
fd2ecd885b
commit
da573eaa3a
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@ -58,6 +58,7 @@
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#include <linux/delay.h>
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#include <linux/sizes.h>
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#include <linux/ntb.h>
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#include <linux/mutex.h>
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#define DRIVER_NAME "ntb_perf"
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#define DRIVER_DESCRIPTION "PCIe NTB Performance Measurement Tool"
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@ -121,6 +122,7 @@ struct pthr_ctx {
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int dma_prep_err;
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int src_idx;
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void *srcs[MAX_SRCS];
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wait_queue_head_t *wq;
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};
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struct perf_ctx {
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@ -134,9 +136,11 @@ struct perf_ctx {
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struct dentry *debugfs_run;
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struct dentry *debugfs_threads;
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u8 perf_threads;
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bool run;
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/* mutex ensures only one set of threads run at once */
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struct mutex run_mutex;
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struct pthr_ctx pthr_ctx[MAX_THREADS];
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atomic_t tsync;
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atomic_t tdone;
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};
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enum {
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@ -295,12 +299,18 @@ static int perf_move_data(struct pthr_ctx *pctx, char __iomem *dst, char *src,
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set_current_state(TASK_INTERRUPTIBLE);
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schedule_timeout(1);
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}
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if (unlikely(kthread_should_stop()))
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break;
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}
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if (use_dma) {
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pr_info("%s: All DMA descriptors submitted\n", current->comm);
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while (atomic_read(&pctx->dma_sync) != 0)
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while (atomic_read(&pctx->dma_sync) != 0) {
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if (kthread_should_stop())
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break;
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msleep(20);
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}
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}
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kstop = ktime_get();
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@ -393,7 +403,10 @@ static int ntb_perf_thread(void *data)
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pctx->srcs[i] = NULL;
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}
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return 0;
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atomic_inc(&perf->tdone);
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wake_up(pctx->wq);
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rc = 0;
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goto done;
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err:
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for (i = 0; i < MAX_SRCS; i++) {
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@ -406,6 +419,16 @@ err:
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pctx->dma_chan = NULL;
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}
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done:
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/* Wait until we are told to stop */
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for (;;) {
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set_current_state(TASK_INTERRUPTIBLE);
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if (kthread_should_stop())
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break;
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schedule();
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}
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__set_current_state(TASK_RUNNING);
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return rc;
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}
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@ -553,6 +576,7 @@ static ssize_t debugfs_run_read(struct file *filp, char __user *ubuf,
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struct perf_ctx *perf = filp->private_data;
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char *buf;
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ssize_t ret, out_offset;
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int running;
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if (!perf)
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return 0;
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@ -560,7 +584,9 @@ static ssize_t debugfs_run_read(struct file *filp, char __user *ubuf,
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buf = kmalloc(64, GFP_KERNEL);
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if (!buf)
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return -ENOMEM;
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out_offset = snprintf(buf, 64, "%d\n", perf->run);
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running = mutex_is_locked(&perf->run_mutex);
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out_offset = snprintf(buf, 64, "%d\n", running);
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ret = simple_read_from_buffer(ubuf, count, offp, buf, out_offset);
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kfree(buf);
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@ -572,7 +598,6 @@ static void threads_cleanup(struct perf_ctx *perf)
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struct pthr_ctx *pctx;
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int i;
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perf->run = false;
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for (i = 0; i < MAX_THREADS; i++) {
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pctx = &perf->pthr_ctx[i];
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if (pctx->thread) {
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@ -587,65 +612,66 @@ static ssize_t debugfs_run_write(struct file *filp, const char __user *ubuf,
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{
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struct perf_ctx *perf = filp->private_data;
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int node, i;
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DECLARE_WAIT_QUEUE_HEAD(wq);
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if (!perf->link_is_up)
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return 0;
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return -ENOLINK;
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if (perf->perf_threads == 0)
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return 0;
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return -EINVAL;
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if (atomic_read(&perf->tsync) == 0)
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perf->run = false;
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if (perf->run)
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threads_cleanup(perf);
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else {
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perf->run = true;
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if (perf->perf_threads > MAX_THREADS) {
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perf->perf_threads = MAX_THREADS;
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pr_info("Reset total threads to: %u\n", MAX_THREADS);
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}
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/* no greater than 1M */
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if (seg_order > MAX_SEG_ORDER) {
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seg_order = MAX_SEG_ORDER;
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pr_info("Fix seg_order to %u\n", seg_order);
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}
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if (run_order < seg_order) {
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run_order = seg_order;
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pr_info("Fix run_order to %u\n", run_order);
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}
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node = dev_to_node(&perf->ntb->pdev->dev);
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/* launch kernel thread */
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for (i = 0; i < perf->perf_threads; i++) {
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struct pthr_ctx *pctx;
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pctx = &perf->pthr_ctx[i];
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atomic_set(&pctx->dma_sync, 0);
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pctx->perf = perf;
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pctx->thread =
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kthread_create_on_node(ntb_perf_thread,
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(void *)pctx,
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node, "ntb_perf %d", i);
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if (IS_ERR(pctx->thread)) {
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pctx->thread = NULL;
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goto err;
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} else
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wake_up_process(pctx->thread);
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if (perf->run == false)
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return -ENXIO;
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}
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if (!mutex_trylock(&perf->run_mutex))
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return -EBUSY;
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if (perf->perf_threads > MAX_THREADS) {
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perf->perf_threads = MAX_THREADS;
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pr_info("Reset total threads to: %u\n", MAX_THREADS);
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}
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/* no greater than 1M */
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if (seg_order > MAX_SEG_ORDER) {
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seg_order = MAX_SEG_ORDER;
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pr_info("Fix seg_order to %u\n", seg_order);
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}
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if (run_order < seg_order) {
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run_order = seg_order;
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pr_info("Fix run_order to %u\n", run_order);
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}
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node = dev_to_node(&perf->ntb->pdev->dev);
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atomic_set(&perf->tdone, 0);
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/* launch kernel thread */
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for (i = 0; i < perf->perf_threads; i++) {
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struct pthr_ctx *pctx;
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pctx = &perf->pthr_ctx[i];
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atomic_set(&pctx->dma_sync, 0);
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pctx->perf = perf;
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pctx->wq = &wq;
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pctx->thread =
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kthread_create_on_node(ntb_perf_thread,
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(void *)pctx,
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node, "ntb_perf %d", i);
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if (IS_ERR(pctx->thread)) {
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pctx->thread = NULL;
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goto err;
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} else {
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wake_up_process(pctx->thread);
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}
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}
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wait_event_interruptible(wq,
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atomic_read(&perf->tdone) == perf->perf_threads);
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threads_cleanup(perf);
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mutex_unlock(&perf->run_mutex);
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return count;
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err:
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threads_cleanup(perf);
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mutex_unlock(&perf->run_mutex);
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return -ENXIO;
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}
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@ -713,7 +739,7 @@ static int perf_probe(struct ntb_client *client, struct ntb_dev *ntb)
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perf->ntb = ntb;
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perf->perf_threads = 1;
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atomic_set(&perf->tsync, 0);
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perf->run = false;
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mutex_init(&perf->run_mutex);
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spin_lock_init(&perf->db_lock);
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perf_setup_mw(ntb, perf);
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INIT_DELAYED_WORK(&perf->link_work, perf_link_work);
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@ -748,6 +774,8 @@ static void perf_remove(struct ntb_client *client, struct ntb_dev *ntb)
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dev_dbg(&perf->ntb->dev, "%s called\n", __func__);
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mutex_lock(&perf->run_mutex);
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cancel_delayed_work_sync(&perf->link_work);
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cancel_work_sync(&perf->link_cleanup);
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