netfs: zero the tail of a short DIO/unbuffered readgrafted

The buffered read collector zero-fills the tail of a short read that
stops below the inode's i_size (netfs_clear_unread()), so a read that
races an extending write still returns the expected number of bytes.
The non-buffered collector path does no such thing: it just records
how much was transferred.

Add the same zero-fill for the non-buffered case, gated on
NETFS_SREQ_CLEAR_TAIL: a subreq's source sets that flag when a short
result from it is known to be safe to treat as a hole, as opposed to
NETFS_SREQ_HIT_EOF, which means the read genuinely ran off the end of
the file and should be reported short as-is. Only CLEAR_TAIL should
zero-fill here; a real EOF must stay a real short read.

No source currently sets CLEAR_TAIL on an unbuffered/DIO subrequest,
so this is inert on its own -- a following change teaches cifs to set
it in the one case that needs it.

Fixes: e2d46f2ec332 ("netfs: Change the read result collector to only use one work item")
Reviewed-by: David Howells <dhowells@redhat.com>
Reviewed-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: Paulo Alcantara <pc@manguebit.org>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Ronnie Sahlberg <ronniesahlberg@gmail.com>
Cc: Shyam Prasad N <sprasad@microsoft.com>
Cc: Tom Talpey <tom@talpey.com>
Cc: Bharath SM <bharathsm@microsoft.com>
Cc: stable@vger.kernel.org

1 files changed, 218 insertions, 0 deletions

diff --git a/drivers/gpu/host1x/debug.c b/drivers/gpu/host1x/debug.c
new file mode 100644
index 000000000..b828f773f
--- /dev/null
+++ b/drivers/gpu/host1x/debug.c
@@ -0,0 +1,218 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) 2010 Google, Inc.
+ * Author: Erik Gilling <konkers@android.com>
+ *
+ * Copyright (C) 2011-2013 NVIDIA Corporation
+ */
+
+#include <linux/debugfs.h>
+#include <linux/pm_runtime.h>
+#include <linux/seq_file.h>
+#include <linux/uaccess.h>
+
+#include <linux/io.h>
+
+#include "dev.h"
+#include "debug.h"
+#include "channel.h"
+
+static DEFINE_MUTEX(debug_lock);
+
+unsigned int host1x_debug_trace_cmdbuf;
+
+static pid_t host1x_debug_force_timeout_pid;
+static u32 host1x_debug_force_timeout_val;
+static u32 host1x_debug_force_timeout_channel;
+
+void host1x_debug_output(struct output *o, const char *fmt, ...)
+{
+	va_list args;
+	int len;
+
+	va_start(args, fmt);
+	len = vscnprintf(o->buf, sizeof(o->buf), fmt, args);
+	va_end(args);
+
+	o->fn(o->ctx, o->buf, len, false);
+}
+
+void host1x_debug_cont(struct output *o, const char *fmt, ...)
+{
+	va_list args;
+	int len;
+
+	va_start(args, fmt);
+	len = vscnprintf(o->buf, sizeof(o->buf), fmt, args);
+	va_end(args);
+
+	o->fn(o->ctx, o->buf, len, true);
+}
+
+static int show_channel(struct host1x_channel *ch, void *data, bool show_fifo)
+{
+	struct host1x *m = dev_get_drvdata(ch->dev->parent);
+	struct output *o = data;
+	int err;
+
+	err = pm_runtime_resume_and_get(m->dev);
+	if (err < 0)
+		return err;
+
+	mutex_lock(&ch->cdma.lock);
+	mutex_lock(&debug_lock);
+
+	if (show_fifo)
+		host1x_hw_show_channel_fifo(m, ch, o);
+
+	host1x_hw_show_channel_cdma(m, ch, o);
+
+	mutex_unlock(&debug_lock);
+	mutex_unlock(&ch->cdma.lock);
+
+	pm_runtime_put(m->dev);
+
+	return 0;
+}
+
+static void show_syncpts(struct host1x *m, struct output *o, bool show_all)
+{
+	unsigned long irqflags;
+	struct list_head *pos;
+	unsigned int i;
+	int err;
+
+	host1x_debug_output(o, "---- syncpts ----\n");
+
+	err = pm_runtime_resume_and_get(m->dev);
+	if (err < 0)
+		return;
+
+	for (i = 0; i < host1x_syncpt_nb_pts(m); i++) {
+		u32 max = host1x_syncpt_read_max(m->syncpt + i);
+		u32 min = host1x_syncpt_load(m->syncpt + i);
+		unsigned int waiters = 0;
+
+		spin_lock_irqsave(&m->syncpt[i].fences.lock, irqflags);
+		list_for_each(pos, &m->syncpt[i].fences.list)
+			waiters++;
+		spin_unlock_irqrestore(&m->syncpt[i].fences.lock, irqflags);
+
+		if (!kref_read(&m->syncpt[i].ref))
+			continue;
+
+		if (!show_all && !min && !max && !waiters)
+			continue;
+
+		host1x_debug_output(o,
+				    "id %u (%s) min %d max %d (%d waiters)\n",
+				    i, m->syncpt[i].name, min, max, waiters);
+	}
+
+	for (i = 0; i < host1x_syncpt_nb_bases(m); i++) {
+		u32 base_val;
+
+		base_val = host1x_syncpt_load_wait_base(m->syncpt + i);
+		if (base_val)
+			host1x_debug_output(o, "waitbase id %u val %d\n", i,
+					    base_val);
+	}
+
+	pm_runtime_put(m->dev);
+
+	host1x_debug_output(o, "\n");
+}
+
+static void show_all(struct host1x *m, struct output *o, bool show_fifo)
+{
+	unsigned int i;
+
+	host1x_hw_show_mlocks(m, o);
+	show_syncpts(m, o, true);
+	host1x_debug_output(o, "---- channels ----\n");
+
+	for (i = 0; i < m->info->nb_channels; ++i) {
+		struct host1x_channel *ch = host1x_channel_get_index(m, i);
+
+		if (ch) {
+			show_channel(ch, o, show_fifo);
+			host1x_channel_put(ch);
+		}
+	}
+}
+
+static int host1x_debug_all_show(struct seq_file *s, void *unused)
+{
+	struct output o = {
+		.fn = write_to_seqfile,
+		.ctx = s
+	};
+
+	show_all(s->private, &o, true);
+
+	return 0;
+}
+DEFINE_SHOW_ATTRIBUTE(host1x_debug_all);
+
+static int host1x_debug_show(struct seq_file *s, void *unused)
+{
+	struct output o = {
+		.fn = write_to_seqfile,
+		.ctx = s
+	};
+
+	show_all(s->private, &o, false);
+
+	return 0;
+}
+DEFINE_SHOW_ATTRIBUTE(host1x_debug);
+
+static void host1x_debugfs_init(struct host1x *host1x)
+{
+	struct dentry *de = debugfs_create_dir("tegra-host1x", NULL);
+
+	/* Store the created entry */
+	host1x->debugfs = de;
+
+	debugfs_create_file("status", S_IRUGO, de, host1x, &host1x_debug_fops);
+	debugfs_create_file("status_all", S_IRUGO, de, host1x,
+			    &host1x_debug_all_fops);
+
+	debugfs_create_u32("trace_cmdbuf", S_IRUGO|S_IWUSR, de,
+			   &host1x_debug_trace_cmdbuf);
+
+	host1x_hw_debug_init(host1x, de);
+
+	debugfs_create_u32("force_timeout_pid", S_IRUGO|S_IWUSR, de,
+			   &host1x_debug_force_timeout_pid);
+	debugfs_create_u32("force_timeout_val", S_IRUGO|S_IWUSR, de,
+			   &host1x_debug_force_timeout_val);
+	debugfs_create_u32("force_timeout_channel", S_IRUGO|S_IWUSR, de,
+			   &host1x_debug_force_timeout_channel);
+}
+
+static void host1x_debugfs_exit(struct host1x *host1x)
+{
+	debugfs_remove_recursive(host1x->debugfs);
+}
+
+void host1x_debug_init(struct host1x *host1x)
+{
+	if (IS_ENABLED(CONFIG_DEBUG_FS))
+		host1x_debugfs_init(host1x);
+}
+
+void host1x_debug_deinit(struct host1x *host1x)
+{
+	if (IS_ENABLED(CONFIG_DEBUG_FS))
+		host1x_debugfs_exit(host1x);
+}
+
+void host1x_debug_dump(struct host1x *host1x)
+{
+	struct output o = {
+		.fn = write_to_printk
+	};
+
+	show_all(host1x, &o, true);
+}