[PATCH v4 18/40] powerpc: optimize arch code by using atomic find_bit() API

[Yury Norov]

Use find_and_{set,clear}_bit() where appropriate and simplify the logic.

Signed-off-by: Yury Norov <yury.norov at gmail.com>
---
 arch/powerpc/mm/book3s32/mmu_context.c     | 11 +++---
 arch/powerpc/platforms/pasemi/dma_lib.c    | 46 ++++++----------------
 arch/powerpc/platforms/powernv/pci-sriov.c | 13 ++----
 3 files changed, 20 insertions(+), 50 deletions(-)

diff --git a/arch/powerpc/mm/book3s32/mmu_context.c b/arch/powerpc/mm/book3s32/mmu_context.c
index 1922f9a6b058..ece7b55b6cdb 100644
--- a/arch/powerpc/mm/book3s32/mmu_context.c
+++ b/arch/powerpc/mm/book3s32/mmu_context.c
@@ -17,6 +17,7 @@
  *    Copyright (C) 1991, 1992, 1993, 1994  Linus Torvalds
  */
 
+#include <linux/find_atomic.h>
 #include <linux/mm.h>
 #include <linux/init.h>
 #include <linux/export.h>
@@ -50,13 +51,11 @@ static unsigned long context_map[LAST_CONTEXT / BITS_PER_LONG + 1];
 
 unsigned long __init_new_context(void)
 {
-	unsigned long ctx = next_mmu_context;
+	unsigned long ctx;
 
-	while (test_and_set_bit(ctx, context_map)) {
-		ctx = find_next_zero_bit(context_map, LAST_CONTEXT+1, ctx);
-		if (ctx > LAST_CONTEXT)
-			ctx = 0;
-	}
+	ctx = find_and_set_next_bit(context_map, LAST_CONTEXT + 1, next_mmu_context);
+	if (ctx > LAST_CONTEXT)
+		ctx = 0;
 	next_mmu_context = (ctx + 1) & LAST_CONTEXT;
 
 	return ctx;
diff --git a/arch/powerpc/platforms/pasemi/dma_lib.c b/arch/powerpc/platforms/pasemi/dma_lib.c
index 1be1f18f6f09..db008902e5f3 100644
--- a/arch/powerpc/platforms/pasemi/dma_lib.c
+++ b/arch/powerpc/platforms/pasemi/dma_lib.c
@@ -5,6 +5,7 @@
  * Common functions for DMA access on PA Semi PWRficient
  */
 
+#include <linux/find_atomic.h>
 #include <linux/kernel.h>
 #include <linux/export.h>
 #include <linux/pci.h>
@@ -118,14 +119,9 @@ static int pasemi_alloc_tx_chan(enum pasemi_dmachan_type type)
 		limit = MAX_TXCH;
 		break;
 	}
-retry:
-	bit = find_next_bit(txch_free, MAX_TXCH, start);
-	if (bit >= limit)
-		return -ENOSPC;
-	if (!test_and_clear_bit(bit, txch_free))
-		goto retry;
-
-	return bit;
+
+	bit = find_and_clear_next_bit(txch_free, MAX_TXCH, start);
+	return bit < limit ? bit : -ENOSPC;
 }
 
 static void pasemi_free_tx_chan(int chan)
@@ -136,15 +132,9 @@ static void pasemi_free_tx_chan(int chan)
 
 static int pasemi_alloc_rx_chan(void)
 {
-	int bit;
-retry:
-	bit = find_first_bit(rxch_free, MAX_RXCH);
-	if (bit >= MAX_TXCH)
-		return -ENOSPC;
-	if (!test_and_clear_bit(bit, rxch_free))
-		goto retry;
-
-	return bit;
+	int bit = find_and_clear_bit(rxch_free, MAX_RXCH);
+
+	return bit < MAX_TXCH ? bit : -ENOSPC;
 }
 
 static void pasemi_free_rx_chan(int chan)
@@ -374,16 +364,9 @@ EXPORT_SYMBOL(pasemi_dma_free_buf);
  */
 int pasemi_dma_alloc_flag(void)
 {
-	int bit;
+	int bit = find_and_clear_bit(flags_free, MAX_FLAGS);
 
-retry:
-	bit = find_first_bit(flags_free, MAX_FLAGS);
-	if (bit >= MAX_FLAGS)
-		return -ENOSPC;
-	if (!test_and_clear_bit(bit, flags_free))
-		goto retry;
-
-	return bit;
+	return bit < MAX_FLAGS ? bit : -ENOSPC;
 }
 EXPORT_SYMBOL(pasemi_dma_alloc_flag);
 
@@ -439,16 +422,9 @@ EXPORT_SYMBOL(pasemi_dma_clear_flag);
  */
 int pasemi_dma_alloc_fun(void)
 {
-	int bit;
-
-retry:
-	bit = find_first_bit(fun_free, MAX_FLAGS);
-	if (bit >= MAX_FLAGS)
-		return -ENOSPC;
-	if (!test_and_clear_bit(bit, fun_free))
-		goto retry;
+	int bit = find_and_clear_bit(fun_free, MAX_FLAGS);
 
-	return bit;
+	return bit < MAX_FLAGS ? bit : -ENOSPC;
 }
 EXPORT_SYMBOL(pasemi_dma_alloc_fun);
 
diff --git a/arch/powerpc/platforms/powernv/pci-sriov.c b/arch/powerpc/platforms/powernv/pci-sriov.c
index cc7b1dd54ac6..e33e57c559f7 100644
--- a/arch/powerpc/platforms/powernv/pci-sriov.c
+++ b/arch/powerpc/platforms/powernv/pci-sriov.c
@@ -3,6 +3,7 @@
 #include <linux/kernel.h>
 #include <linux/ioport.h>
 #include <linux/bitmap.h>
+#include <linux/find_atomic.h>
 #include <linux/pci.h>
 
 #include <asm/opal.h>
@@ -397,18 +398,12 @@ static int64_t pnv_ioda_map_m64_single(struct pnv_phb *phb,
 
 static int pnv_pci_alloc_m64_bar(struct pnv_phb *phb, struct pnv_iov_data *iov)
 {
-	int win;
+	int win = find_and_set_bit(&phb->ioda.m64_bar_alloc, phb->ioda.m64_bar_idx + 1);
 
-	do {
-		win = find_next_zero_bit(&phb->ioda.m64_bar_alloc,
-				phb->ioda.m64_bar_idx + 1, 0);
-
-		if (win >= phb->ioda.m64_bar_idx + 1)
-			return -1;
-	} while (test_and_set_bit(win, &phb->ioda.m64_bar_alloc));
+	if (win >= phb->ioda.m64_bar_idx + 1)
+		return -1;
 
 	set_bit(win, iov->used_m64_bar_mask);
-
 	return win;
 }
 
-- 
2.43.0