linux-kernel - [PATCH -mm 2/4] alpha: IOMMU had better access to the free space bitmap at only one place

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Date:	Sat, 23 Feb 2008 15:13:13 +0900
From:	FUJITA Tomonori <fujita.tomonori@....ntt.co.jp>
To:	linux-kernel@...r.kernel.org
Cc:	tomof@....org, FUJITA Tomonori <fujita.tomonori@....ntt.co.jp>,
	Richard Henderson <rth@...ddle.net>,
	Ivan Kokshaysky <ink@...assic.park.msu.ru>,
	Andrew Morton <akpm@...ux-foundation.org>
Subject: [PATCH -mm 2/4] alpha: IOMMU had better access to the free space bitmap at only one place

iommu_arena_find_pages duplicates the code to access to the bitmap for
free space management. This patch convert the IOMMU code to have only
one place to access the bitmap, in the popular way that other IOMMUs
(e.g. POWER and SPARC) do.

This patch is preparation for modifications to fix the IOMMU segment
boundary problem.

Signed-off-by: FUJITA Tomonori <fujita.tomonori@....ntt.co.jp>
Cc: Richard Henderson <rth@...ddle.net>
Cc: Ivan Kokshaysky <ink@...assic.park.msu.ru>
Cc: Andrew Morton <akpm@...ux-foundation.org>
---
 arch/alpha/kernel/pci_iommu.c |   28 +++++++++++++++-------------
 1 files changed, 15 insertions(+), 13 deletions(-)

diff --git a/arch/alpha/kernel/pci_iommu.c b/arch/alpha/kernel/pci_iommu.c
index bbf9990..e54f829 100644
--- a/arch/alpha/kernel/pci_iommu.c
+++ b/arch/alpha/kernel/pci_iommu.c
@@ -132,12 +132,15 @@ iommu_arena_find_pages(struct pci_iommu_arena *arena, long n, long mask)
 {
 	unsigned long *ptes;
 	long i, p, nent;
+	int pass = 0;
 
 	/* Search forward for the first mask-aligned sequence of N free ptes */
 	ptes = arena->ptes;
 	nent = arena->size >> PAGE_SHIFT;
 	p = ALIGN(arena->next_entry, mask + 1);
 	i = 0;
+
+again:
 	while (i < n && p+i < nent) {
 		if (ptes[p+i])
 			p = ALIGN(p + i + 1, mask + 1), i = 0;
@@ -146,19 +149,18 @@ iommu_arena_find_pages(struct pci_iommu_arena *arena, long n, long mask)
 	}
 
 	if (i < n) {
-                /* Reached the end.  Flush the TLB and restart the
-                   search from the beginning.  */
-		alpha_mv.mv_pci_tbi(arena->hose, 0, -1);
-
-		p = 0, i = 0;
-		while (i < n && p+i < nent) {
-			if (ptes[p+i])
-				p = ALIGN(p + i + 1, mask + 1), i = 0;
-			else
-				i = i + 1;
-		}
-
-		if (i < n)
+		if (pass < 1) {
+			/*
+			 * Reached the end.  Flush the TLB and restart
+			 * the search from the beginning.
+			*/
+			alpha_mv.mv_pci_tbi(arena->hose, 0, -1);
+
+			pass++;
+			p = 0;
+			i = 0;
+			goto again;
+		} else
 			return -1;
 	}
 
-- 
1.5.3.4

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