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2176c6b599
Redesign the creation of ALSA controls so that the cs_dsp pwr_lock is not held when calling snd_ctl_add(). Instead of creating the ALSA control from the cs_dsp control_add callback, do it after cs_dsp_power_up() has completed. The existing functions are changed to return void instead of passing errors back - this duplicates the original behaviour, as cs_dsp does not abort firmware load if creation of a control fails. It is safe to walk the control list without taking any mutex provided that the caller is not trying to load a new firmware or remove the driver in parallel. There is no other situation that the list can change. So the caller can trigger creation of ALSA controls after cs_dsp_power_up() has returned. A cs_dsp control will have a non-NULL priv pointer if we have created an ALSA control. With the previous code the ALSA controls were created from the cs_dsp control_add callback. But this is called with pwr_lock held (as it is part of the DSP power-up sequence). The kernel lock checking will show a mutex inversion between this and the control creation path: control_add pwr_lock held, takes controls_rwsem (in snd_ctl_add) get/put controls_rwsem held, takes pwr_lock to call cs_dsp. This is not completely theoretical. Although the time window is very small, it is possible for these to run in parallel and deadlock the old implementation. Signed-off-by: Richard Fitzgerald <rf@opensource.cirrus.com> Signed-off-by: Stefan Binding <sbinding@opensource.cirrus.com> Link: https://lore.kernel.org/r/20221011143552.621792-4-sbinding@opensource.cirrus.com Signed-off-by: Takashi Iwai <tiwai@suse.de>
40 lines
1 KiB
C
40 lines
1 KiB
C
/* SPDX-License-Identifier: GPL-2.0
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*
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* HDA DSP ALSA Control Driver
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*
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* Copyright 2022 Cirrus Logic, Inc.
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*
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* Author: Stefan Binding <sbinding@opensource.cirrus.com>
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*/
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#ifndef __HDA_CS_DSP_CTL_H__
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#define __HDA_CS_DSP_CTL_H__
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#include <sound/soc.h>
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#include <linux/firmware/cirrus/cs_dsp.h>
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enum hda_cs_dsp_fw_id {
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HDA_CS_DSP_FW_SPK_PROT,
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HDA_CS_DSP_FW_SPK_CALI,
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HDA_CS_DSP_FW_SPK_DIAG,
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HDA_CS_DSP_FW_MISC,
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HDA_CS_DSP_NUM_FW
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};
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struct hda_cs_dsp_ctl_info {
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struct snd_card *card;
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enum hda_cs_dsp_fw_id fw_type;
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const char *device_name;
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};
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extern const char * const hda_cs_dsp_fw_ids[HDA_CS_DSP_NUM_FW];
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void hda_cs_dsp_add_controls(struct cs_dsp *dsp, const struct hda_cs_dsp_ctl_info *info);
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void hda_cs_dsp_control_remove(struct cs_dsp_coeff_ctl *cs_ctl);
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int hda_cs_dsp_write_ctl(struct cs_dsp *dsp, const char *name, int type,
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unsigned int alg, const void *buf, size_t len);
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int hda_cs_dsp_read_ctl(struct cs_dsp *dsp, const char *name, int type,
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unsigned int alg, void *buf, size_t len);
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#endif /*__HDA_CS_DSP_CTL_H__*/
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