Hi Jiri, On Wed, Sep 11, 2024 at 03:27:32PM +0200, Jiri Kosina wrote: > On Mon, 9 Sep 2024, Dmitry Torokhov wrote: > > > i2c-hid uses 2 shared buffers: command and "raw" input buffer for > > sending requests to peripherals and read data from peripherals when > > executing variety of commands. Such commands include reading of HID > > registers, requesting particular power mode, getting and setting > > reports and so on. Because all such requests use the same 2 buffers > > they should not execute simultaneously. > > > > Fix this by introducing "cmd_lock" mutex and acquire it whenever > > we needs to access ihid->cmdbuf or idid->rawbuf. > > > > Signed-off-by: Dmitry Torokhov <dmitry.torokhov@xxxxxxxxx> > > Thanks for the fix, Dmitry. Out of curiosity, did you find it by code > inspection, or have you actually seen it happening for real, making the > driver misbehave? No, I have not observed this issue in the wild, that is why I di dnot tag it explicitly for stable. It came about when I was reviewing Goodix HID SPI driver, noticed that it was using a shared buffer, asked to and locking, and realized that I2C HID needed the same. And just got around to sending out the fix... As far as I can see USB HID driver does not need it - it does not share URBs but rather allocates new one for each request (via usb_control_msg()). Thanks. -- Dmitry
