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soundwire: use driver callbacks directly with proper locking
In the SoundWire probe, we store a pointer from the driver ops into the 'slave' structure. This can lead to kernel oopses when unbinding codec drivers, e.g. with the following sequence to remove machine driver and codec driver. /sbin/modprobe -r snd_soc_sof_sdw /sbin/modprobe -r snd_soc_rt711 The full details can be found in the BugLink below, for reference the two following examples show different cases of driver ops/callbacks being invoked after the driver .remove(). kernel: BUG: kernel NULL pointer dereference, address: 0000000000000150 kernel: Workqueue: events cdns_update_slave_status_work [soundwire_cadence] kernel: RIP: 0010:mutex_lock+0x19/0x30 kernel: Call Trace: kernel: ? sdw_handle_slave_status+0x426/0xe00 [soundwire_bus 94ff184bf398570c3f8ff7efe9e32529f532e4ae] kernel: ? newidle_balance+0x26a/0x400 kernel: ? cdns_update_slave_status_work+0x1e9/0x200 [soundwire_cadence 1bcf98eebe5ba9833cd433323769ac923c9c6f82] kernel: BUG: unable to handle page fault for address: ffffffffc07654c8 kernel: Workqueue: pm pm_runtime_work kernel: RIP: 0010:sdw_bus_prep_clk_stop+0x6f/0x160 [soundwire_bus] kernel: Call Trace: kernel: <TASK> kernel: sdw_cdns_clock_stop+0xb5/0x1b0 [soundwire_cadence 1bcf98eebe5ba9833cd433323769ac923c9c6f82] kernel: intel_suspend_runtime+0x5f/0x120 [soundwire_intel aca858f7c87048d3152a4a41bb68abb9b663a1dd] kernel: ? dpm_sysfs_remove+0x60/0x60 This was not detected earlier in Intel tests since the tests first remove the parent PCI device and shut down the bus. The sequence above is a corner case which keeps the bus operational but without a driver bound. This patch removes the use the 'slave' ops and uses proper locking to make sure there are no live callbacks based on a dangling pointer executed during or after the driver unbinding sequence. In one specific case, indicated with comments in the code, the device lock is already taken at a higher level when starting the resume operations. The issue with the ops pointer has been there since December 2017, but there were so many changes in the bus handling code that this patch will not apply cleanly all the way to this initial commit. The changes can be easily backported though. Thanks to Dan Williams for his suggestions on an earlier version of this patch. BugLink: thesofproject#3531 Fixes: 56d4fe3 ("soundwire: Add MIPI DisCo property helpers") Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
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