6.18-stable review patch. If anyone has any objections, please let me know.
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From: Oliver Neukum oneukum@suse.com
[ Upstream commit a2fa8a12e6bc9d89c0505b8dd7ae38ec173d25de ]
A failure to take a lock with O_NONBLOCK needs to result in -EAGAIN. Change it.
Fixes: 66e3e591891da ("usb: Add driver for Altus Metrum ChaosKey device (v2)") Signed-off-by: Oliver Neukum oneukum@suse.com Link: https://patch.msgid.link/20251030093918.2248104-1-oneukum@suse.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/usb/misc/chaoskey.c | 16 +++++++++++++--- 1 file changed, 13 insertions(+), 3 deletions(-)
diff --git a/drivers/usb/misc/chaoskey.c b/drivers/usb/misc/chaoskey.c index 225863321dc47..45cff32656c6e 100644 --- a/drivers/usb/misc/chaoskey.c +++ b/drivers/usb/misc/chaoskey.c @@ -444,9 +444,19 @@ static ssize_t chaoskey_read(struct file *file, goto bail; mutex_unlock(&dev->rng_lock);
- result = mutex_lock_interruptible(&dev->lock); - if (result) - goto bail; + if (file->f_flags & O_NONBLOCK) { + result = mutex_trylock(&dev->lock); + if (result == 0) { + result = -EAGAIN; + goto bail; + } else { + result = 0; + } + } else { + result = mutex_lock_interruptible(&dev->lock); + if (result) + goto bail; + } if (dev->valid == dev->used) { result = _chaoskey_fill(dev); if (result < 0) {