ASoC: Add support for GPIOs driven amplifiers

Herve Codina <herve.codina@bootlin.com> says:

On some embedded system boards, audio amplifiers are designed using
discrete components such as op-amp, several resistors and switches to
either adjust the gain (switching resistors) or fully switch the
audio signal path (mute and/or bypass features).

Those switches are usually driven by simple GPIOs.

This kind of amplifiers are not handled in ASoC and the fallback is to
let the user-space handle those GPIOs out of the ALSA world.

In order to have those kind of amplifiers fully integrated in the audio
stack, this series introduces the audio-gpio-amp to handle them.

This new ASoC component allows to have the amplifiers seen as ASoC
auxiliarty devices and so it allows to control them through audio mixer
controls.

In order to ease the review, I choose to split modifications related
to the merge of the gpio-audio-amp part into the simple-amplfier driver
in several commits.

Link: https://patch.msgid.link/20260513081702.317117-1-herve.codina@bootlin.com

4 files changed, 49 insertions, 23 deletions

diff --git a/lib/kunit/Kconfig b/lib/kunit/Kconfig
index 498cc51e493d..94ff8e4089bf 100644
--- a/lib/kunit/Kconfig
+++ b/lib/kunit/Kconfig
@@ -16,8 +16,9 @@ menuconfig KUNIT
 if KUNIT
 
 config KUNIT_DEBUGFS
-	bool "KUnit - Enable /sys/kernel/debug/kunit debugfs representation" if !KUNIT_ALL_TESTS
-	default KUNIT_ALL_TESTS
+	bool "KUnit - Enable /sys/kernel/debug/kunit debugfs representation"
+	depends on DEBUG_FS
+	default y
 	help
 	  Enable debugfs representation for kunit.  Currently this consists
 	  of /sys/kernel/debug/kunit/<test_suite>/results files for each
diff --git a/lib/rhashtable.c b/lib/rhashtable.c
index 7a67ef5b67b6..04b3a808fca9 100644
--- a/lib/rhashtable.c
+++ b/lib/rhashtable.c
@@ -114,6 +114,14 @@ static void bucket_table_free(const struct bucket_table *tbl)
 	kvfree(tbl);
 }
 
+static void bucket_table_free_atomic(const struct bucket_table *tbl)
+{
+	if (tbl->nest)
+		nested_bucket_table_free(tbl);
+
+	kvfree_atomic(tbl);
+}
+
 static void bucket_table_free_rcu(struct rcu_head *head)
 {
 	bucket_table_free(container_of(head, struct bucket_table, rcu));
@@ -496,7 +504,7 @@ static int rhashtable_insert_rehash(struct rhashtable *ht,
 
 	err = rhashtable_rehash_attach(ht, tbl, new_tbl);
 	if (err) {
-		bucket_table_free(new_tbl);
+		bucket_table_free_atomic(new_tbl);
 		if (err == -EEXIST)
 			err = 0;
 	} else
@@ -1166,6 +1174,11 @@ static void rhashtable_free_one(struct rhashtable *ht, struct rhash_head *obj,
  * This function will eventually sleep to wait for an async resize
  * to complete. The caller is responsible that no further write operations
  * occurs in parallel.
+ *
+ * After cancel_work_sync() has returned, the deferred rehash worker is
+ * quiesced and, per the contract above, no other concurrent access to the
+ * rhashtable is possible. The tables are therefore owned exclusively by
+ * this function and can be walked without ht->mutex held.
  */
 void rhashtable_free_and_destroy(struct rhashtable *ht,
 				 void (*free_fn)(void *ptr, void *arg),
@@ -1177,8 +1190,15 @@ void rhashtable_free_and_destroy(struct rhashtable *ht,
 	irq_work_sync(&ht->run_irq_work);
 	cancel_work_sync(&ht->run_work);
 
-	mutex_lock(&ht->mutex);
-	tbl = rht_dereference(ht->tbl, ht);
+	/*
+	 * Do NOT take ht->mutex here. The rehash worker establishes
+	 * ht->mutex -> fs_reclaim via GFP_KERNEL bucket allocation under
+	 * the mutex; callers on the reclaim path (e.g. simple_xattr_ht_free()
+	 * from evict() under the dcache shrinker for shmem/kernfs/pidfs
+	 * inodes) would otherwise close a circular dependency
+	 * fs_reclaim -> ht->mutex.
+	 */
+	tbl = rcu_dereference_raw(ht->tbl);
 restart:
 	if (free_fn) {
 		for (i = 0; i < tbl->size; i++) {
@@ -1187,22 +1207,21 @@ restart:
 			cond_resched();
 			for (pos = rht_ptr_exclusive(rht_bucket(tbl, i)),
 			     next = !rht_is_a_nulls(pos) ?
-					rht_dereference(pos->next, ht) : NULL;
+					rcu_dereference_raw(pos->next) : NULL;
 			     !rht_is_a_nulls(pos);
 			     pos = next,
 			     next = !rht_is_a_nulls(pos) ?
-					rht_dereference(pos->next, ht) : NULL)
+					rcu_dereference_raw(pos->next) : NULL)
 				rhashtable_free_one(ht, pos, free_fn, arg);
 		}
 	}
 
-	next_tbl = rht_dereference(tbl->future_tbl, ht);
+	next_tbl = rcu_dereference_raw(tbl->future_tbl);
 	bucket_table_free(tbl);
 	if (next_tbl) {
 		tbl = next_tbl;
 		goto restart;
 	}
-	mutex_unlock(&ht->mutex);
 }
 EXPORT_SYMBOL_GPL(rhashtable_free_and_destroy);
 
diff --git a/lib/tests/test_kprobes.c b/lib/tests/test_kprobes.c
index b7582010125c..06e729e4de05 100644
--- a/lib/tests/test_kprobes.c
+++ b/lib/tests/test_kprobes.c
@@ -12,6 +12,12 @@
 
 #define div_factor 3
 
+#define KP_CLEAR(_kp) \
+do { \
+	(_kp).addr = NULL; \
+	(_kp).flags = 0; \
+} while (0)
+
 static u32 rand1, preh_val, posth_val;
 static u32 (*target)(u32 value);
 static u32 (*recursed_target)(u32 value);
@@ -125,10 +131,6 @@ static void test_kprobes(struct kunit *test)
 
 	current_test = test;
 
-	/* addr and flags should be cleard for reusing kprobe. */
-	kp.addr = NULL;
-	kp.flags = 0;
-
 	KUNIT_EXPECT_EQ(test, 0, register_kprobes(kps, 2));
 	preh_val = 0;
 	posth_val = 0;
@@ -226,9 +228,6 @@ static void test_kretprobes(struct kunit *test)
 	struct kretprobe *rps[2] = {&rp, &rp2};
 
 	current_test = test;
-	/* addr and flags should be cleard for reusing kprobe. */
-	rp.kp.addr = NULL;
-	rp.kp.flags = 0;
 	KUNIT_EXPECT_EQ(test, 0, register_kretprobes(rps, 2));
 
 	krph_val = 0;
@@ -290,8 +289,6 @@ static void test_stacktrace_on_kretprobe(struct kunit *test)
 	unsigned long myretaddr = (unsigned long)__builtin_return_address(0);
 
 	current_test = test;
-	rp3.kp.addr = NULL;
-	rp3.kp.flags = 0;
 
 	/*
 	 * Run the stacktrace_driver() to record correct return address in
@@ -352,8 +349,6 @@ static void test_stacktrace_on_nested_kretprobe(struct kunit *test)
 	struct kretprobe *rps[2] = {&rp3, &rp4};
 
 	current_test = test;
-	rp3.kp.addr = NULL;
-	rp3.kp.flags = 0;
 
 	//KUNIT_ASSERT_NE(test, myretaddr, stacktrace_driver());
 
@@ -367,6 +362,18 @@ static void test_stacktrace_on_nested_kretprobe(struct kunit *test)
 
 static int kprobes_test_init(struct kunit *test)
 {
+	KP_CLEAR(kp);
+	KP_CLEAR(kp2);
+	KP_CLEAR(kp_missed);
+#ifdef CONFIG_KRETPROBES
+	KP_CLEAR(rp.kp);
+	KP_CLEAR(rp2.kp);
+#ifdef CONFIG_ARCH_CORRECT_STACKTRACE_ON_KRETPROBE
+	KP_CLEAR(rp3.kp);
+	KP_CLEAR(rp4.kp);
+#endif
+#endif
+
 	target = kprobe_target;
 	target2 = kprobe_target2;
 	recursed_target = kprobe_recursed_target;
diff --git a/lib/vdso/gettimeofday.c b/lib/vdso/gettimeofday.c
index a5798bd26d20..da224011fafd 100644
--- a/lib/vdso/gettimeofday.c
+++ b/lib/vdso/gettimeofday.c
@@ -248,11 +248,10 @@ bool do_aux(const struct vdso_time_data *vd, clockid_t clock, struct __kernel_ti
 	vc = &vd->aux_clock_data[idx];
 
 	do {
-		if (vdso_read_begin_timens(vc, &seq)) {
+		while (vdso_read_begin_timens(vc, &seq)) {
+			/* Re-read from the real time data page, reload seq by looping */
 			vd = __arch_get_vdso_u_timens_data(vd);
 			vc = &vd->aux_clock_data[idx];
-			/* Re-read from the real time data page */
-			continue;
 		}
 
 		/* Auxclock disabled? */