This is a note to let you know that I've just added the patch titled
HID: i2c-hid: remove I2C_HID_READ_PENDING flag to prevent lock-up
to the 5.10-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
hid-i2c-hid-remove-i2c_hid_read_pending-flag-to-prevent-lock-up.patch
and it can be found in the queue-5.10 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 9c0f59e47a90c54d0153f8ddc0f80d7a36207d0e Mon Sep 17 00:00:00 2001
From: Nam Cao <namcao@xxxxxxxxxxxxx>
Date: Mon, 18 Mar 2024 11:59:02 +0100
Subject: HID: i2c-hid: remove I2C_HID_READ_PENDING flag to prevent lock-up
From: Nam Cao <namcao@xxxxxxxxxxxxx>
commit 9c0f59e47a90c54d0153f8ddc0f80d7a36207d0e upstream.
The flag I2C_HID_READ_PENDING is used to serialize I2C operations.
However, this is not necessary, because I2C core already has its own
locking for that.
More importantly, this flag can cause a lock-up: if the flag is set in
i2c_hid_xfer() and an interrupt happens, the interrupt handler
(i2c_hid_irq) will check this flag and return immediately without doing
anything, then the interrupt handler will be invoked again in an
infinite loop.
Since interrupt handler is an RT task, it takes over the CPU and the
flag-clearing task never gets scheduled, thus we have a lock-up.
Delete this unnecessary flag.
Reported-and-tested-by: Eva Kurchatova <nyandarknessgirl@xxxxxxxxx>
Closes: https://lore.kernel.org/r/CA+eeCSPUDpUg76ZO8dszSbAGn+UHjcyv8F1J-CUPVARAzEtW9w@xxxxxxxxxxxxxx
Fixes: 4a200c3b9a40 ("HID: i2c-hid: introduce HID over i2c specification implementation")
Cc: <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Nam Cao <namcao@xxxxxxxxxxxxx>
Signed-off-by: Jiri Kosina <jkosina@xxxxxxxx>
[apply to v4.19 -> v5.15]
Signed-off-by: Nam Cao <namcao@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/hid/i2c-hid/i2c-hid-core.c | 8 --------
1 file changed, 8 deletions(-)
--- a/drivers/hid/i2c-hid/i2c-hid-core.c
+++ b/drivers/hid/i2c-hid/i2c-hid-core.c
@@ -56,7 +56,6 @@
/* flags */
#define I2C_HID_STARTED 0
#define I2C_HID_RESET_PENDING 1
-#define I2C_HID_READ_PENDING 2
#define I2C_HID_PWR_ON 0x00
#define I2C_HID_PWR_SLEEP 0x01
@@ -256,7 +255,6 @@ static int __i2c_hid_command(struct i2c_
msg[1].len = data_len;
msg[1].buf = buf_recv;
msg_num = 2;
- set_bit(I2C_HID_READ_PENDING, &ihid->flags);
}
if (wait)
@@ -264,9 +262,6 @@ static int __i2c_hid_command(struct i2c_
ret = i2c_transfer(client->adapter, msg, msg_num);
- if (data_len > 0)
- clear_bit(I2C_HID_READ_PENDING, &ihid->flags);
-
if (ret != msg_num)
return ret < 0 ? ret : -EIO;
@@ -538,9 +533,6 @@ static irqreturn_t i2c_hid_irq(int irq,
{
struct i2c_hid *ihid = dev_id;
- if (test_bit(I2C_HID_READ_PENDING, &ihid->flags))
- return IRQ_HANDLED;
-
i2c_hid_get_input(ihid);
return IRQ_HANDLED;
Patches currently in stable-queue which might be from namcao@xxxxxxxxxxxxx are
queue-5.10/hid-i2c-hid-remove-i2c_hid_read_pending-flag-to-prevent-lock-up.patch
