iwlwifi: pcie: fix RF-Kill vs. firmware load race
When we load the firmware, we hold trans_pcie->mutex to avoid nested flows. We also rely on the ISR to wake up the thread when the DMA has finished copying a chunk. During this flow, we enable the RF-Kill interrupt. The problem is that the RF-Kill interrupt handler can take the mutex and bring the device down. This means that if we load the firmware while the RF-Kill switch is enabled (which will happen when we load the INIT firmware to read the device's capabilities and register to mac80211), we may get an RF-Kill interrupt immediately and the ISR will be waiting for the mutex held by the thread that is currently loading the firmware. At this stage, the ISR won't be able to service the DMA's interrupt needed to wake up the thread that load the firmware. We are in a deadlock situation which ends when the thread that loads the firmware fails on timeout and releases the mutex. To fix this, take the mutex later in the flow, disable the interrupts and synchronize_irq() to give a chance to the RF-Kill interrupt to run and complete. After that, mask all the interrupts besides the DMA interrupt and proceed with firmware load. Make sure to check that there was no RF-Kill interrupt when the interrupts were disabled. This fixes https://bugzilla.kernel.org/show_bug.cgi?id=111361Signed-off-by:Emmanuel Grumbach <emmanuel.grumbach@intel.com>
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