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From:   "Joel Fernandes (Google)" <joel@joelfernandes.org>
To:     linux-kernel@vger.kernel.org
Cc:     Vineeth Pillai <viremana@linux.microsoft.com>,
        Joel Fernandes <joel@joelfernandes.org>,
        Aaron Lu <aaron.lwe@gmail.com>,
        Aubrey Li <aubrey.li@linux.intel.com>,
        Julien Desfossez <jdesfossez@digitalocean.com>,
        Kees Cook <keescook@chromium.org>,
        "Paul E. McKenney" <paulmck@kernel.org>,
        Paul Turner <pjt@google.com>,
        Peter Zijlstra <peterz@infradead.org>,
        Steven Rostedt <rostedt@goodmis.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        Tim Chen <tim.c.chen@intel.com>,
        Tim Chen <tim.c.chen@linux.intel.com>,
        Vincent Guittot <vincent.guittot@linaro.org>,
        x86@kernel.org (maintainer:X86 ARCHITECTURE (32-BIT AND 64-BIT)),
        fweisbec@gmail.com, kerrnel@google.com,
        Phil Auld <pauld@redhat.com>,
        Valentin Schneider <valentin.schneider@arm.com>,
        Paolo Bonzini <pbonzini@redhat.com>,
        Chen Yu <yu.c.chen@intel.com>,
        Christian Brauner <christian.brauner@ubuntu.com>
Subject: [PATCH RFC 07/12] bitops: Introduce find_next_or_bit
Date:   Fri, 14 Aug 2020 23:19:03 -0400
Message-Id: <20200815031908.1015049-8-joel@joelfernandes.org>
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From: Vineeth Pillai <viremana@linux.microsoft.com>

Hotplug fixes to core-scheduling require a new bitops API.

Introduce a new API find_next_or_bit() which returns the bit number of
the next set bit in OR-ed bit masks of the given bit masks.

Signed-off-by: Vineeth Pillai <viremana@linux.microsoft.com>
Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org>
---
 include/asm-generic/bitops/find.h | 16 +++++++++
 lib/find_bit.c                    | 56 +++++++++++++++++++++++++------
 2 files changed, 61 insertions(+), 11 deletions(-)

diff --git a/include/asm-generic/bitops/find.h b/include/asm-generic/bitops/find.h
index 9fdf21302fdf..0b476ca0d665 100644
--- a/include/asm-generic/bitops/find.h
+++ b/include/asm-generic/bitops/find.h
@@ -32,6 +32,22 @@ extern unsigned long find_next_and_bit(const unsigned long *addr1,
 		unsigned long offset);
 #endif
 
+#ifndef find_next_or_bit
+/**
+ * find_next_or_bit - find the next set bit in any memory regions
+ * @addr1: The first address to base the search on
+ * @addr2: The second address to base the search on
+ * @offset: The bitnumber to start searching at
+ * @size: The bitmap size in bits
+ *
+ * Returns the bit number for the next set bit
+ * If no bits are set, returns @size.
+ */
+extern unsigned long find_next_or_bit(const unsigned long *addr1,
+		const unsigned long *addr2, unsigned long size,
+		unsigned long offset);
+#endif
+
 #ifndef find_next_zero_bit
 /**
  * find_next_zero_bit - find the next cleared bit in a memory region
diff --git a/lib/find_bit.c b/lib/find_bit.c
index 49f875f1baf7..2eca8e2b16b1 100644
--- a/lib/find_bit.c
+++ b/lib/find_bit.c
@@ -19,7 +19,14 @@
 
 #if !defined(find_next_bit) || !defined(find_next_zero_bit) ||			\
 	!defined(find_next_bit_le) || !defined(find_next_zero_bit_le) ||	\
-	!defined(find_next_and_bit)
+	!defined(find_next_and_bit) || !defined(find_next_or_bit)
+
+typedef enum {
+	FNB_AND = 0,
+	FNB_OR  = 1,
+	FNB_MAX = 2
+} fnb_bwops_t;
+
 /*
  * This is a common helper function for find_next_bit, find_next_zero_bit, and
  * find_next_and_bit. The differences are:
@@ -29,7 +36,8 @@
  */
 static unsigned long _find_next_bit(const unsigned long *addr1,
 		const unsigned long *addr2, unsigned long nbits,
-		unsigned long start, unsigned long invert, unsigned long le)
+		unsigned long start, unsigned long invert,
+		fnb_bwops_t type, unsigned long le)
 {
 	unsigned long tmp, mask;
 
@@ -37,8 +45,16 @@ static unsigned long _find_next_bit(const unsigned long *addr1,
 		return nbits;
 
 	tmp = addr1[start / BITS_PER_LONG];
-	if (addr2)
-		tmp &= addr2[start / BITS_PER_LONG];
+	if (addr2) {
+		switch (type) {
+		case FNB_AND:
+			tmp &= addr2[start / BITS_PER_LONG];
+			break;
+		case FNB_OR:
+			tmp |= addr2[start / BITS_PER_LONG];
+			break;
+		}
+	}
 	tmp ^= invert;
 
 	/* Handle 1st word. */
@@ -56,8 +72,16 @@ static unsigned long _find_next_bit(const unsigned long *addr1,
 			return nbits;
 
 		tmp = addr1[start / BITS_PER_LONG];
-		if (addr2)
-			tmp &= addr2[start / BITS_PER_LONG];
+		if (addr2) {
+			switch (type) {
+			case FNB_AND:
+				tmp &= addr2[start / BITS_PER_LONG];
+				break;
+			case FNB_OR:
+				tmp |= addr2[start / BITS_PER_LONG];
+				break;
+			}
+		}
 		tmp ^= invert;
 	}
 
@@ -75,7 +99,7 @@ static unsigned long _find_next_bit(const unsigned long *addr1,
 unsigned long find_next_bit(const unsigned long *addr, unsigned long size,
 			    unsigned long offset)
 {
-	return _find_next_bit(addr, NULL, size, offset, 0UL, 0);
+	return _find_next_bit(addr, NULL, size, offset, 0UL, FNB_AND, 0);
 }
 EXPORT_SYMBOL(find_next_bit);
 #endif
@@ -84,7 +108,7 @@ EXPORT_SYMBOL(find_next_bit);
 unsigned long find_next_zero_bit(const unsigned long *addr, unsigned long size,
 				 unsigned long offset)
 {
-	return _find_next_bit(addr, NULL, size, offset, ~0UL, 0);
+	return _find_next_bit(addr, NULL, size, offset, ~0UL, FNB_AND, 0);
 }
 EXPORT_SYMBOL(find_next_zero_bit);
 #endif
@@ -94,11 +118,21 @@ unsigned long find_next_and_bit(const unsigned long *addr1,
 		const unsigned long *addr2, unsigned long size,
 		unsigned long offset)
 {
-	return _find_next_bit(addr1, addr2, size, offset, 0UL, 0);
+	return _find_next_bit(addr1, addr2, size, offset, 0UL, FNB_AND, 0);
 }
 EXPORT_SYMBOL(find_next_and_bit);
 #endif
 
+#if !defined(find_next_or_bit)
+unsigned long find_next_or_bit(const unsigned long *addr1,
+		const unsigned long *addr2, unsigned long size,
+		unsigned long offset)
+{
+	return _find_next_bit(addr1, addr2, size, offset, 0UL, FNB_OR, 0);
+}
+EXPORT_SYMBOL(find_next_or_bit);
+#endif
+
 #ifndef find_first_bit
 /*
  * Find the first set bit in a memory region.
@@ -161,7 +195,7 @@ EXPORT_SYMBOL(find_last_bit);
 unsigned long find_next_zero_bit_le(const void *addr, unsigned
 		long size, unsigned long offset)
 {
-	return _find_next_bit(addr, NULL, size, offset, ~0UL, 1);
+	return _find_next_bit(addr, NULL, size, offset, ~0UL, FNB_AND, 1);
 }
 EXPORT_SYMBOL(find_next_zero_bit_le);
 #endif
@@ -170,7 +204,7 @@ EXPORT_SYMBOL(find_next_zero_bit_le);
 unsigned long find_next_bit_le(const void *addr, unsigned
 		long size, unsigned long offset)
 {
-	return _find_next_bit(addr, NULL, size, offset, 0UL, 1);
+	return _find_next_bit(addr, NULL, size, offset, 0UL, FNB_AND, 1);
 }
 EXPORT_SYMBOL(find_next_bit_le);
 #endif
-- 
2.28.0.220.ged08abb693-goog