Merge tag 'trace-v7.3-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-tracegrafted

Pull tracing fixes from Steven Rostedt:

 - Don't destroy user event fields when removal fails

   User event fields are destroyed before the event is removed from
   visibility. But that can fail leaving the still visible event with no
   fields. Move the destroying of the fields to after the event is
   successfully removed from visibility.

 - Initialize function graph state is fork before calling
   copy_exec_state()

   For non-CLONE_VM forks, copy_exec_state() allocates a new
   task_exec_state. If that allocation fails, ftrace_graph_exit_task()
   will free the tasks ret_stack pointer. Since that pointer is still
   using the parent's ret_stack, it mistakenly frees the parent's
   pointer too.

   Call ftrace_graph_init() on the task first which will NULL out the
   new tasks's ret_stack and if the copy fails, it will not free
   anything.

 - Remove FGRAPH_MAX_INDEX

   The macro FGRAPH_MAX_INDEX was added but never used. Remove it.

 - Save ent_size in function graph printing of nested functions

   The function graph tracer needs to look at the next event to see if
   the next event is the return of the current function entry. If it is,
   it prints a single line:

	ktime_get();

   Otherwise it prints it like a nested function:

	tick_nohz_irq_exit() {
	    ktime_get();
	    kcpustat_irq_exit();
	}

   In order to look at the next event, it must save the current event so
   that it has the information to print from it. It saves the event in
   the iterator descriptor called "ent". What it doesn't save is the
   ent_size of the event which is now used to know if the function graph
   arguments are to be printed. The peek doesn't save the size so the
   size used happens to be that of the size of the last event that was
   seen.

   Save the entry event size in the iterator descriptor so that the
   correct size is used.

 - Fix several errors with freeing data in the histogram code

   The histogram code had a lot of leaked or or incorrect accounting
   when failures happen. Correct them.

 - Fix histogram regression of .percent and .graph modifiers

   Up until 6.3 histogram values could have "percent" or "graph"
   modifiers that changed how they were printed. But a change that added
   restricting histograms values from being strings, stack traces and
   other modifiers inadvertently prevented them from using the percent
   and graph modifiers, which were legal use cases for values.

   Put back the percent and graph modifiers.

 - Fix various typos in the comments

 - Set the trace_clock before initializing a histogram with clock
   argument

   The histogram API allows the user to specific which trace clock to
   use via a "clock=" string. The histogram is set up first before the
   clock is checked. If the passed in clock is not valid, it exits
   without fully fixing up the histogram leaving it on the list and a
   use-after-free can trigger.

   Update the clock argument first and if it fails then exit gracefully
   before the histogram trigger is placed on any lists.

 - Restore :mod: trailer after parsing in ftrace_set_clr_event

   The function ftrace_set_clr_event() modifies the parse string and
   needs to put it back to what was passed in. It searches for ":mod:"
   via a strsep() but fails to put back the first ':' in the string.

   Add back the ':' in the passed in string.

 - Take trace_array reference when opening a tracer options file

   The options files are dynamically created and some tracers add their
   own options. When a tracer adds their own list of options, the
   trace_array holding them has an array to hold the list of options for
   each tracer. This array increases in size via a krealloc(), and the
   new entry gets a newly allocated array to hold the options of the new
   tracer being added.

   The element in each entry of the tracer's option array holds a
   pointer back to the trace_array, a pointer to the tracer it is
   associated to, a pointer to the flags of the option.

   The issue is that these arrays are freed when the trace_array is
   freed when its instance it represents is removed from the instances
   directory. There's a race that an open of one of these options files
   can happen when the instance is being removed.

   Add a new helper function to be called by the open function of the
   options file to iterate all existing trace_arrays under a lock and
   find the one that has the given option element in one of it's tracer
   arrays. If found, then update the associated trace_array's reference
   counter to keep it from being freed. If not found, have the open call
   return -ENODEV.

 - Disable interrupts when acquiring the lock in rb_wake_up_waiters()

   The function rb_wake_up_waiters() assumes it will be called in
   interrupt context and does not disable irqs when taking
   cpu_buffer->reader_lock, which can be called in hard interrupt
   context. The issue is in PREEMPT_RT, this function is called in
   thread context leaving this lock open to a deadlock.

   Take the lock with interrupts disabled.

 - Use rcu_assign_pointer() for tmp_ops filter hash

   The tmp_ops used in update_ftrace_direct_mod() assigns its
   filter_hash field directly, but that field is annotated as __rcu and
   sparse complains. Assign it with rcu_assign_pointer()

 - Fix use-after-free in enable_trigger_private_data_free()

   The trace_event_call is accessed through the event_trigger_data's
   trace_event_file pointer to put the trace_event_call on freeing. The
   issue is that the trace_event_file data may have been freed already
   causing a use-after-free. Add a field to the event_trigger_data that
   points directly to the trace_event_call so that it can decrement its
   reference directly without needing to go through the
   trace_event_file.

 - Fix accounting of buffer data remote headers

   trace_buffer_desc_size() and trace_remote_alloc_buffer() undercount
   the number of pages is needed for the asked for size as it doesn't
   take into account the meta data on each page. Add a helper function
   to do the calculation properly and use that in these functions.

 - Catch nr_page_va overflow in ring_buffer_desc sizing

   The number of pages per remote ring buffer is capped by
   ring_buffer_desc::nr_page_va (32 bits). A buffer_size large enough to
   overflow that field would silently allocate a descriptor smaller than
   what was asked for.

 - Do not resize the subbuf order if any per_cpu buffer is disabled

   The mmapping of ring buffers disables resizing the subbuffers, but it
   is done per-cpu whereas the subbuf size change is done for all the
   per_cpu buffers under the buffer->mutex. It could change the size of
   some while the mapping is happening on others. Have the resize of the
   subbuf order check all the per_cpu buffers under the lock to see if
   any of them is disabled before starting and causing an inconsistency
   between buffers that are being mapped.

* tag 'trace-v7.3-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace: (25 commits)
  ring-buffer: Check resize_disabled before publishing the new subbuf order
  tracing/remotes: Catch nr_page_va overflow in ring_buffer_desc sizing
  tracing/remotes: Account for ring buffer page header in size calculation
  tracing: Don't dereference trace_event_file in deferred trigger free
  ftrace: Use rcu_assign_pointer() for tmp_ops filter hash
  ring-buffer: Acquire the lock with irqsave in rb_wake_up_waiters()
  tracing: Take trace_array reference when opening a tracer options file
  tracing: Fix ring_buffer_read_page_size() kernel-doc
  tracing: Restore :mod: trailer after parsing in ftrace_set_clr_event()
  tracing: Fix memory corruption from a "STACKTRACE" histogram key
  tracing: Fix memory corruption from the histogram stacktrace modifier
  tracing: Undo the registration when enabling the histogram trigger fails
  tracing: Take the reference before publishing the named histogram trigger
  tracing: Set the trace clock before registering the histogram trigger
  tracing: Fix typo "preceeded" in comment
  tracing: Fix typo "availabe" in comment
  tracing: Let histogram values keep the percent and graph modifiers
  tracing: Keep the entry count when the histogram stats allocation fails
  tracing: Free histogram the field rejected for a bad modifier
  tracing: Free histogram the var ref when its initialization fails
  ...

1 files changed, 620 insertions, 0 deletions

diff --git a/drivers/input/serio/libps2.c b/drivers/input/serio/libps2.c
new file mode 100644
index 000000000..05b64277a
--- /dev/null
+++ b/drivers/input/serio/libps2.c
@@ -0,0 +1,620 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * PS/2 driver library
+ *
+ * Copyright (c) 1999-2002 Vojtech Pavlik
+ * Copyright (c) 2004 Dmitry Torokhov
+ */
+
+
+#include <linux/delay.h>
+#include <linux/export.h>
+#include <linux/module.h>
+#include <linux/sched.h>
+#include <linux/interrupt.h>
+#include <linux/input.h>
+#include <linux/kmsan-checks.h>
+#include <linux/serio.h>
+#include <linux/i8042.h>
+#include <linux/libps2.h>
+
+#define DRIVER_DESC	"PS/2 driver library"
+
+#define PS2_CMD_SETSCALE11	0x00e6
+#define PS2_CMD_SETRES		0x10e8
+#define PS2_CMD_EX_SETLEDS	0x20eb
+#define PS2_CMD_SETLEDS		0x10ed
+#define PS2_CMD_GETID		0x02f2
+#define PS2_CMD_SETREP		0x10f3 /* Set repeat rate/set report rate */
+#define PS2_CMD_RESET_BAT	0x02ff
+
+#define PS2_RET_BAT		0xaa
+#define PS2_RET_ID		0x00
+#define PS2_RET_ACK		0xfa
+#define PS2_RET_NAK		0xfe
+#define PS2_RET_ERR		0xfc
+
+#define PS2_FLAG_ACK		BIT(0)	/* Waiting for ACK/NAK */
+#define PS2_FLAG_CMD		BIT(1)	/* Waiting for a command to finish */
+#define PS2_FLAG_CMD1		BIT(2)	/* Waiting for the first byte of command response */
+#define PS2_FLAG_WAITID		BIT(3)	/* Command executing is GET ID */
+#define PS2_FLAG_NAK		BIT(4)	/* Last transmission was NAKed */
+#define PS2_FLAG_PASS_NOACK	BIT(5)	/* Pass non-ACK byte to receive handler */
+
+static int ps2_do_sendbyte(struct ps2dev *ps2dev, u8 byte,
+			   unsigned int timeout, unsigned int max_attempts)
+	__releases(&ps2dev->serio->lock) __acquires(&ps2dev->serio->lock)
+{
+	int attempt = 0;
+	int error;
+
+	lockdep_assert_held(&ps2dev->serio->lock);
+
+	do {
+		ps2dev->nak = 1;
+		ps2dev->flags |= PS2_FLAG_ACK;
+
+		serio_continue_rx(ps2dev->serio);
+
+		error = serio_write(ps2dev->serio, byte);
+		if (error)
+			dev_dbg(&ps2dev->serio->dev,
+				"failed to write %#02x: %d\n", byte, error);
+		else
+			wait_event_timeout(ps2dev->wait,
+					   !(ps2dev->flags & PS2_FLAG_ACK),
+					   msecs_to_jiffies(timeout));
+
+		serio_pause_rx(ps2dev->serio);
+	} while (ps2dev->nak == PS2_RET_NAK && ++attempt < max_attempts);
+
+	ps2dev->flags &= ~PS2_FLAG_ACK;
+
+	if (!error) {
+		switch (ps2dev->nak) {
+		case 0:
+			break;
+		case PS2_RET_NAK:
+			error = -EAGAIN;
+			break;
+		case PS2_RET_ERR:
+			error = -EPROTO;
+			break;
+		default:
+			error = -EIO;
+			break;
+		}
+	}
+
+	if (error || attempt > 1)
+		dev_dbg(&ps2dev->serio->dev,
+			"%02x - %d (%x), attempt %d\n",
+			byte, error, ps2dev->nak, attempt);
+
+	return error;
+}
+
+/**
+ * ps2_sendbyte - sends a byte to the device and wait for acknowledgement
+ * @ps2dev: a PS/2 device to send the data to
+ * @byte: data to be sent to the device
+ * @timeout: timeout for sending the data and receiving an acknowledge
+ *
+ * The function doesn't handle retransmission, the caller is expected to handle
+ * it when needed.
+ *
+ * ps2_sendbyte() can only be called from a process context.
+ */
+int ps2_sendbyte(struct ps2dev *ps2dev, u8 byte, unsigned int timeout)
+{
+	int retval;
+
+	guard(serio_pause_rx)(ps2dev->serio);
+
+	retval = ps2_do_sendbyte(ps2dev, byte, timeout, 1);
+	dev_dbg(&ps2dev->serio->dev, "%02x - %x\n", byte, ps2dev->nak);
+
+	return retval;
+}
+EXPORT_SYMBOL(ps2_sendbyte);
+
+/**
+ * ps2_begin_command - mark beginning of execution of a complex command
+ * @ps2dev: a PS/2 device executing the command
+ *
+ * Serializes a complex/compound command. Once command is finished
+ * ps2_end_command() should be called.
+ */
+void ps2_begin_command(struct ps2dev *ps2dev)
+{
+	struct mutex *m = ps2dev->serio->ps2_cmd_mutex ?: &ps2dev->cmd_mutex;
+
+	mutex_lock(m);
+}
+EXPORT_SYMBOL(ps2_begin_command);
+
+/**
+ * ps2_end_command - mark end of execution of a complex command
+ * @ps2dev: a PS/2 device executing the command
+ */
+void ps2_end_command(struct ps2dev *ps2dev)
+{
+	struct mutex *m = ps2dev->serio->ps2_cmd_mutex ?: &ps2dev->cmd_mutex;
+
+	mutex_unlock(m);
+}
+EXPORT_SYMBOL(ps2_end_command);
+
+/**
+ * ps2_drain - waits for device to transmit requested number of bytes
+ * and discards them
+ * @ps2dev: the PS/2 device that should be drained
+ * @maxbytes: maximum number of bytes to be drained
+ * @timeout: time to drain the device
+ */
+void ps2_drain(struct ps2dev *ps2dev, size_t maxbytes, unsigned int timeout)
+{
+	if (WARN_ON(maxbytes > sizeof(ps2dev->cmdbuf)))
+		maxbytes = sizeof(ps2dev->cmdbuf);
+
+	ps2_begin_command(ps2dev);
+
+	scoped_guard(serio_pause_rx, ps2dev->serio) {
+		ps2dev->flags = PS2_FLAG_CMD;
+		ps2dev->cmdcnt = maxbytes;
+	}
+
+	wait_event_timeout(ps2dev->wait,
+			   !(ps2dev->flags & PS2_FLAG_CMD),
+			   msecs_to_jiffies(timeout));
+
+	ps2_end_command(ps2dev);
+}
+EXPORT_SYMBOL(ps2_drain);
+
+/**
+ * ps2_is_keyboard_id - checks received ID byte against the list of
+ *   known keyboard IDs
+ * @id_byte: data byte that should be checked
+ */
+bool ps2_is_keyboard_id(u8 id_byte)
+{
+	static const u8 keyboard_ids[] = {
+		0xab,	/* Regular keyboards		*/
+		0xac,	/* NCD Sun keyboard		*/
+		0x2b,	/* Trust keyboard, translated	*/
+		0x5d,	/* Trust keyboard		*/
+		0x60,	/* NMB SGI keyboard, translated */
+		0x47,	/* NMB SGI keyboard		*/
+	};
+
+	return memchr(keyboard_ids, id_byte, sizeof(keyboard_ids)) != NULL;
+}
+EXPORT_SYMBOL(ps2_is_keyboard_id);
+
+/*
+ * ps2_adjust_timeout() is called after receiving 1st byte of command
+ * response and tries to reduce remaining timeout to speed up command
+ * completion.
+ */
+static int ps2_adjust_timeout(struct ps2dev *ps2dev,
+			      unsigned int command, unsigned int timeout)
+{
+	switch (command) {
+	case PS2_CMD_RESET_BAT:
+		/*
+		 * Device has sent the first response byte after
+		 * reset command, reset is thus done, so we can
+		 * shorten the timeout.
+		 * The next byte will come soon (keyboard) or not
+		 * at all (mouse).
+		 */
+		if (timeout > msecs_to_jiffies(100))
+			timeout = msecs_to_jiffies(100);
+		break;
+
+	case PS2_CMD_GETID:
+		/*
+		 * Microsoft Natural Elite keyboard responds to
+		 * the GET ID command as it were a mouse, with
+		 * a single byte. Fail the command so atkbd will
+		 * use alternative probe to detect it.
+		 */
+		if (ps2dev->cmdbuf[1] == 0xaa) {
+			scoped_guard(serio_pause_rx, ps2dev->serio)
+				ps2dev->flags = 0;
+
+			timeout = 0;
+		}
+
+		/*
+		 * If device behind the port is not a keyboard there
+		 * won't be 2nd byte of ID response.
+		 */
+		if (!ps2_is_keyboard_id(ps2dev->cmdbuf[1])) {
+			scoped_guard(serio_pause_rx, ps2dev->serio)
+				ps2dev->flags = ps2dev->cmdcnt = 0;
+
+			timeout = 0;
+		}
+		break;
+
+	default:
+		break;
+	}
+
+	return timeout;
+}
+
+/**
+ * __ps2_command - send a command to PS/2 device
+ * @ps2dev: the PS/2 device that should execute the command
+ * @param: a buffer containing parameters to be sent along with the command,
+ *   or place where the results of the command execution will be deposited,
+ *   or both
+ * @command: command word that encodes the command itself, as well as number of
+ *   additional parameter bytes that should be sent to the device and expected
+ *   length of the command response
+ *
+ * Not serialized. Callers should use ps2_begin_command() and ps2_end_command()
+ * to ensure proper serialization for complex commands.
+ */
+int __ps2_command(struct ps2dev *ps2dev, u8 *param, unsigned int command)
+{
+	unsigned int timeout;
+	unsigned int send = (command >> 12) & 0xf;
+	unsigned int receive = (command >> 8) & 0xf;
+	int rc;
+	int i;
+	u8 send_param[16];
+
+	if (WARN_ON(receive > sizeof(ps2dev->cmdbuf)))
+		return -EINVAL;
+
+	if (WARN_ON(send && !param))
+		return -EINVAL;
+
+	memcpy(send_param, param, send);
+
+	/*
+	 * Not using guard notation because we need to break critical
+	 * section below while waiting for the response.
+	 */
+	serio_pause_rx(ps2dev->serio);
+
+	ps2dev->cmdcnt = receive;
+
+	switch (command) {
+	case PS2_CMD_GETID:
+		/*
+		 * Some mice do not ACK the "get ID" command, prepare to
+		 * handle this.
+		 */
+		ps2dev->flags = PS2_FLAG_WAITID;
+		break;
+
+	case PS2_CMD_SETLEDS:
+	case PS2_CMD_EX_SETLEDS:
+	case PS2_CMD_SETREP:
+		ps2dev->flags = PS2_FLAG_PASS_NOACK;
+		break;
+
+	default:
+		ps2dev->flags = 0;
+		break;
+	}
+
+	if (receive) {
+		/* Indicate that we expect response to the command. */
+		ps2dev->flags |= PS2_FLAG_CMD | PS2_FLAG_CMD1;
+		if (param)
+			for (i = 0; i < receive; i++)
+				ps2dev->cmdbuf[(receive - 1) - i] = param[i];
+	}
+
+	/*
+	 * Some devices (Synaptics) perform the reset before
+	 * ACKing the reset command, and so it can take a long
+	 * time before the ACK arrives.
+	 */
+	timeout = command == PS2_CMD_RESET_BAT ? 1000 : 200;
+
+	rc = ps2_do_sendbyte(ps2dev, command & 0xff, timeout, 2);
+	if (rc)
+		goto out_reset_flags;
+
+	/* Send command parameters, if any. */
+	for (i = 0; i < send; i++) {
+		rc = ps2_do_sendbyte(ps2dev, param[i], 200, 2);
+		if (rc)
+			goto out_reset_flags;
+	}
+
+	serio_continue_rx(ps2dev->serio);
+
+	/*
+	 * The reset command takes a long time to execute.
+	 */
+	timeout = msecs_to_jiffies(command == PS2_CMD_RESET_BAT ? 4000 : 500);
+
+	timeout = wait_event_timeout(ps2dev->wait,
+				     !(ps2dev->flags & PS2_FLAG_CMD1), timeout);
+
+	if (ps2dev->cmdcnt && !(ps2dev->flags & PS2_FLAG_CMD1)) {
+
+		timeout = ps2_adjust_timeout(ps2dev, command, timeout);
+		wait_event_timeout(ps2dev->wait,
+				   !(ps2dev->flags & PS2_FLAG_CMD), timeout);
+	}
+
+	serio_pause_rx(ps2dev->serio);
+
+	if (param) {
+		for (i = 0; i < receive; i++)
+			param[i] = ps2dev->cmdbuf[(receive - 1) - i];
+		kmsan_unpoison_memory(param, receive);
+	}
+
+	if (ps2dev->cmdcnt &&
+	    (command != PS2_CMD_RESET_BAT || ps2dev->cmdcnt != 1)) {
+		rc = -EPROTO;
+		goto out_reset_flags;
+	}
+
+	rc = 0;
+
+ out_reset_flags:
+	ps2dev->flags = 0;
+	serio_continue_rx(ps2dev->serio);
+
+	dev_dbg(&ps2dev->serio->dev,
+		"%02x [%*ph] - %x/%08lx [%*ph]\n",
+		command & 0xff, send, send_param,
+		ps2dev->nak, ps2dev->flags,
+		receive, param ?: send_param);
+
+	/*
+	 * ps_command() handles resends itself, so do not leak -EAGAIN
+	 * to the callers.
+	 */
+	return rc != -EAGAIN ? rc : -EPROTO;
+}
+EXPORT_SYMBOL(__ps2_command);
+
+/**
+ * ps2_command - send a command to PS/2 device
+ * @ps2dev: the PS/2 device that should execute the command
+ * @param: a buffer containing parameters to be sent along with the command,
+ *   or place where the results of the command execution will be deposited,
+ *   or both
+ * @command: command word that encodes the command itself, as well as number of
+ *   additional parameter bytes that should be sent to the device and expected
+ *   length of the command response
+ *
+ * Note: ps2_command() serializes the command execution so that only one
+ * command can be executed at a time for either individual port or the entire
+ * 8042 controller.
+ */
+int ps2_command(struct ps2dev *ps2dev, u8 *param, unsigned int command)
+{
+	int rc;
+
+	ps2_begin_command(ps2dev);
+	rc = __ps2_command(ps2dev, param, command);
+	ps2_end_command(ps2dev);
+
+	return rc;
+}
+EXPORT_SYMBOL(ps2_command);
+
+/**
+ * ps2_sliced_command - sends an extended PS/2 command to a mouse
+ * @ps2dev: the PS/2 device that should execute the command
+ * @command: command byte
+ *
+ * The command is sent using "sliced" syntax understood by advanced devices,
+ * such as Logitech or Synaptics touchpads. The command is encoded as:
+ * 0xE6 0xE8 rr 0xE8 ss 0xE8 tt 0xE8 uu where (rr*64)+(ss*16)+(tt*4)+uu
+ * is the command.
+ */
+int ps2_sliced_command(struct ps2dev *ps2dev, u8 command)
+{
+	int i;
+	int retval;
+
+	ps2_begin_command(ps2dev);
+
+	retval = __ps2_command(ps2dev, NULL, PS2_CMD_SETSCALE11);
+	if (retval)
+		goto out;
+
+	for (i = 6; i >= 0; i -= 2) {
+		u8 d = (command >> i) & 3;
+		retval = __ps2_command(ps2dev, &d, PS2_CMD_SETRES);
+		if (retval)
+			break;
+	}
+
+out:
+	dev_dbg(&ps2dev->serio->dev, "%02x - %d\n", command, retval);
+	ps2_end_command(ps2dev);
+	return retval;
+}
+EXPORT_SYMBOL(ps2_sliced_command);
+
+/**
+ * ps2_init - initializes ps2dev structure
+ * @ps2dev: structure to be initialized
+ * @serio: serio port associated with the PS/2 device
+ * @pre_receive_handler: validation handler to check basic communication state
+ * @receive_handler: main protocol handler
+ *
+ * Prepares ps2dev structure for use in drivers for PS/2 devices.
+ */
+void ps2_init(struct ps2dev *ps2dev, struct serio *serio,
+	      ps2_pre_receive_handler_t pre_receive_handler,
+	      ps2_receive_handler_t receive_handler)
+{
+	ps2dev->pre_receive_handler = pre_receive_handler;
+	ps2dev->receive_handler = receive_handler;
+
+	mutex_init(&ps2dev->cmd_mutex);
+	lockdep_set_subclass(&ps2dev->cmd_mutex, serio->depth);
+	init_waitqueue_head(&ps2dev->wait);
+	ps2dev->serio = serio;
+	serio_set_drvdata(serio, ps2dev);
+}
+EXPORT_SYMBOL(ps2_init);
+
+/*
+ * ps2_handle_response() stores device's response to a command and notifies
+ * the process waiting for completion of the command. Note that there is a
+ * distinction between waiting for the first byte of the response, and
+ * waiting for subsequent bytes. It is done so that callers could shorten
+ * timeouts once first byte of response is received.
+ */
+static void ps2_handle_response(struct ps2dev *ps2dev, u8 data)
+{
+	if (ps2dev->cmdcnt)
+		ps2dev->cmdbuf[--ps2dev->cmdcnt] = data;
+
+	if (ps2dev->flags & PS2_FLAG_CMD1) {
+		ps2dev->flags &= ~PS2_FLAG_CMD1;
+		if (ps2dev->cmdcnt)
+			wake_up(&ps2dev->wait);
+	}
+
+	if (!ps2dev->cmdcnt) {
+		ps2dev->flags &= ~PS2_FLAG_CMD;
+		wake_up(&ps2dev->wait);
+	}
+}
+
+/*
+ * ps2_handle_ack() processes ACK/NAK of a command from a PS/2 device,
+ * possibly applying workarounds for mice not acknowledging the "get ID"
+ * command.
+ */
+static void ps2_handle_ack(struct ps2dev *ps2dev, u8 data)
+{
+	switch (data) {
+	case PS2_RET_ACK:
+		ps2dev->nak = 0;
+		break;
+
+	case PS2_RET_NAK:
+		ps2dev->flags |= PS2_FLAG_NAK;
+		ps2dev->nak = PS2_RET_NAK;
+		break;
+
+	case PS2_RET_ERR:
+		if (ps2dev->flags & PS2_FLAG_NAK) {
+			ps2dev->flags &= ~PS2_FLAG_NAK;
+			ps2dev->nak = PS2_RET_ERR;
+			break;
+		}
+		fallthrough;
+
+	/*
+	 * Workaround for mice which don't ACK the Get ID command.
+	 * These are valid mouse IDs that we recognize.
+	 */
+	case 0x00:
+	case 0x03:
+	case 0x04:
+		if (ps2dev->flags & PS2_FLAG_WAITID) {
+			ps2dev->nak = 0;
+			break;
+		}
+		fallthrough;
+	default:
+		/*
+		 * Do not signal errors if we get unexpected reply while
+		 * waiting for an ACK to the initial (first) command byte:
+		 * the device might not be quiesced yet and continue
+		 * delivering data. For certain commands (such as set leds and
+		 * set repeat rate) that can be used during normal device
+		 * operation, we even pass this data byte to the normal receive
+		 * handler.
+		 * Note that we reset PS2_FLAG_WAITID flag, so the workaround
+		 * for mice not acknowledging the Get ID command only triggers
+		 * on the 1st byte; if device spews data we really want to see
+		 * a real ACK from it.
+		 */
+		dev_dbg(&ps2dev->serio->dev, "unexpected %#02x\n", data);
+		if (ps2dev->flags & PS2_FLAG_PASS_NOACK)
+			ps2dev->receive_handler(ps2dev, data);
+		ps2dev->flags &= ~(PS2_FLAG_WAITID | PS2_FLAG_PASS_NOACK);
+		return;
+	}
+
+	if (!ps2dev->nak)
+		ps2dev->flags &= ~PS2_FLAG_NAK;
+
+	ps2dev->flags &= ~PS2_FLAG_ACK;
+
+	if (!ps2dev->nak && data != PS2_RET_ACK)
+		ps2_handle_response(ps2dev, data);
+	else
+		wake_up(&ps2dev->wait);
+}
+
+/*
+ * Clears state of PS/2 device after communication error by resetting majority
+ * of flags and waking up waiters, if any.
+ */
+static void ps2_cleanup(struct ps2dev *ps2dev)
+{
+	unsigned long old_flags = ps2dev->flags;
+
+	/* reset all flags except last nak */
+	ps2dev->flags &= PS2_FLAG_NAK;
+
+	if (old_flags & PS2_FLAG_ACK)
+		ps2dev->nak = 1;
+
+	if (old_flags & (PS2_FLAG_ACK | PS2_FLAG_CMD))
+		wake_up(&ps2dev->wait);
+}
+
+/**
+ * ps2_interrupt - common interrupt handler for PS/2 devices
+ * @serio: serio port for the device
+ * @data: a data byte received from the device
+ * @flags: flags such as %SERIO_PARITY or %SERIO_TIMEOUT indicating state of
+ *   the data transfer
+ *
+ * ps2_interrupt() invokes pre-receive handler, optionally handles command
+ * acknowledgement and response from the device, and finally passes the data
+ * to the main protocol handler for future processing.
+ */
+irqreturn_t ps2_interrupt(struct serio *serio, u8 data, unsigned int flags) {
+	struct ps2dev *ps2dev = serio_get_drvdata(serio);
+	enum ps2_disposition rc;
+
+	rc = ps2dev->pre_receive_handler(ps2dev, data, flags);
+	switch (rc) {
+	case PS2_ERROR:
+		ps2_cleanup(ps2dev);
+		break;
+
+	case PS2_IGNORE:
+		break;
+
+	case PS2_PROCESS:
+		if (ps2dev->flags & PS2_FLAG_ACK)
+			ps2_handle_ack(ps2dev, data);
+		else if (ps2dev->flags & PS2_FLAG_CMD)
+			ps2_handle_response(ps2dev, data);
+		else
+			ps2dev->receive_handler(ps2dev, data);
+		break;
+	}
+
+	return IRQ_HANDLED;
+}
+EXPORT_SYMBOL(ps2_interrupt);
+
+MODULE_AUTHOR("Dmitry Torokhov <dtor@mail.ru>");
+MODULE_DESCRIPTION("PS/2 driver library");
+MODULE_LICENSE("GPL");