On Tue, Jul 30, 2024 at 08:31:04AM +0200, Herve Codina wrote:
The carrier_lock spinlock protects the carrier detection. While it is hold, framer_get_status() is called witch in turn takes a mutex. This is not correct and can lead to a deadlock.
A run with PROVE_LOCKING enabled detected the issue: [ BUG: Invalid wait context ] ... c204ddbc (&framer->mutex){+.+.}-{3:3}, at: framer_get_status+0x40/0x78 other info that might help us debug this: context-{4:4} 2 locks held by ifconfig/146: #0: c0926a38 (rtnl_mutex){+.+.}-{3:3}, at: devinet_ioctl+0x12c/0x664 #1: c2006a40 (&qmc_hdlc->carrier_lock){....}-{2:2}, at: qmc_hdlc_framer_set_carrier+0x30/0x98
Avoid the spinlock usage and convert carrier_lock to a mutex.
Fixes: 54762918ca85 ("net: wan: fsl_qmc_hdlc: Add framer support") Cc: stable@vger.kernel.org Signed-off-by: Herve Codina herve.codina@bootlin.com
Reviewed-by: Simon Horman horms@kernel.org