iwlwifi: pcie: fix race in Rx buffer allocator

BugLink: https://bugs.launchpad.net/bugs/1791953

[ Upstream commit 0f22e400 ]

Make sure the rx_allocator worker is canceled before running the
rx_init routine.  rx_init frees and re-allocates all rxb's pages.  The
rx_allocator worker also allocates pages for the used rxb's.  Running
rx_init and rx_allocator simultaniously causes a kernel panic.  Fix
that by canceling the work in rx_init.
Signed-off-by: Shaul Triebitz <shaul.triebitz@intel.com>
Signed-off-by: Luca Coelho <luciano.coelho@intel.com>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Stefan Bader <stefan.bader@canonical.com>
Signed-off-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>

drivers/net/wireless/iwlwifi/pcie/rx.c

@@ -713,6 +713,8 @@ int iwl_pcie_rx_init(struct iwl_trans *trans)
 						WQ_HIGHPRI | WQ_UNBOUND, 1);
 	INIT_WORK(&rba->rx_alloc, iwl_pcie_rx_allocator_work);
 
+	cancel_work_sync(&rba->rx_alloc);
+
 	spin_lock(&rba->lock);
 	atomic_set(&rba->req_pending, 0);
 	atomic_set(&rba->req_ready, 0);