From c41f30e8d2338dd89a2310742e4671ff31c57ea3 Mon Sep 17 00:00:00 2001 From: Rodrigo Rivas Costa Date: Fri, 15 Mar 2019 20:09:10 +0100 Subject: [PATCH] HID: steam: fix deadlock with input devices. [ Upstream commit 6b538cc21334b83f09b25dec4aa2d2726bf07ed0 ] When using this driver with the wireless dongle and some usermode program that monitors every input device (acpid, for example), while another usermode client opens and closes the low-level device repeadedly, the system eventually deadlocks. The reason is that steam_input_register_device() must not be called with the mutex held, because the input subsystem has its own synchronization that clashes with this one: it is possible that steam_input_open() is called before input_register_device() returns, and since steam_input_open() needs to lock the mutex, it deadlocks. However we must hold the mutex when calling any function that sends commands to the controller. If not, random commands end up falling fail. Reported-by: Simon Gene Gottlieb Signed-off-by: Rodrigo Rivas Costa Tested-by: Simon Gene Gottlieb Signed-off-by: Jiri Kosina Signed-off-by: Sasha Levin --- drivers/hid/hid-steam.c | 26 +++++++++++++++++++------- 1 file changed, 19 insertions(+), 7 deletions(-) diff --git a/drivers/hid/hid-steam.c b/drivers/hid/hid-steam.c index 8141cadfca0e..8dae0f9b819e 100644 --- a/drivers/hid/hid-steam.c +++ b/drivers/hid/hid-steam.c @@ -499,6 +499,7 @@ static void steam_battery_unregister(struct steam_device *steam) static int steam_register(struct steam_device *steam) { int ret; + bool client_opened; /* * This function can be called several times in a row with the @@ -511,9 +512,11 @@ static int steam_register(struct steam_device *steam) * Unlikely, but getting the serial could fail, and it is not so * important, so make up a serial number and go on. */ + mutex_lock(&steam->mutex); if (steam_get_serial(steam) < 0) strlcpy(steam->serial_no, "XXXXXXXXXX", sizeof(steam->serial_no)); + mutex_unlock(&steam->mutex); hid_info(steam->hdev, "Steam Controller '%s' connected", steam->serial_no); @@ -528,13 +531,15 @@ static int steam_register(struct steam_device *steam) } mutex_lock(&steam->mutex); - if (!steam->client_opened) { + client_opened = steam->client_opened; + if (!client_opened) steam_set_lizard_mode(steam, lizard_mode); + mutex_unlock(&steam->mutex); + + if (!client_opened) ret = steam_input_register(steam); - } else { + else ret = 0; - } - mutex_unlock(&steam->mutex); return ret; } @@ -630,14 +635,21 @@ static void steam_client_ll_close(struct hid_device *hdev) { struct steam_device *steam = hdev->driver_data; + unsigned long flags; + bool connected; + + spin_lock_irqsave(&steam->lock, flags); + connected = steam->connected; + spin_unlock_irqrestore(&steam->lock, flags); + mutex_lock(&steam->mutex); steam->client_opened = false; + if (connected) + steam_set_lizard_mode(steam, lizard_mode); mutex_unlock(&steam->mutex); - if (steam->connected) { - steam_set_lizard_mode(steam, lizard_mode); + if (connected) steam_input_register(steam); - } } static int steam_client_ll_raw_request(struct hid_device *hdev, -- GitLab