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From:   Helge Deller <deller@gmx.de>
To:     linux@armlinux.org.uk, dinguyen@kernel.org,
        linux-kernel@vger.kernel.org, linux-parisc@vger.kernel.org
Cc:     Helge Deller <deller@gmx.de>
Subject: [PATCH 2/3] nios2: Fix flush_dcache_page() for usage from irq context
Date:   Wed, 24 May 2023 17:26:32 +0200
Message-Id: <20230524152633.203927-3-deller@gmx.de>
In-Reply-To: <20230524152633.203927-1-deller@gmx.de>
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Precedence: bulk

Since at least kernel 6.1, flush_dcache_page() is called with IRQs
disabled, e.g. from aio_complete().

But the current implementation for flush_dcache_page() on NIOS2
unintentionally re-enables IRQs, which may lead to deadlocks.

Fix it by using xa_lock_irqsave() and xa_unlock_irqrestore()
for the flush_dcache_mmap_*lock() macros instead.

Cc: Dinh Nguyen <dinguyen@kernel.org>
Signed-off-by: Helge Deller <deller@gmx.de>
=2D--
 arch/nios2/include/asm/cacheflush.h | 4 ++++
 arch/nios2/mm/cacheflush.c          | 5 +++--
 2 files changed, 7 insertions(+), 2 deletions(-)

diff --git a/arch/nios2/include/asm/cacheflush.h b/arch/nios2/include/asm/=
cacheflush.h
index d0b71dd71287..a37242662809 100644
=2D-- a/arch/nios2/include/asm/cacheflush.h
+++ b/arch/nios2/include/asm/cacheflush.h
@@ -48,5 +48,9 @@ extern void invalidate_dcache_range(unsigned long start,=
 unsigned long end);

 #define flush_dcache_mmap_lock(mapping)		xa_lock_irq(&mapping->i_pages)
 #define flush_dcache_mmap_unlock(mapping)	xa_unlock_irq(&mapping->i_pages=
)
+#define flush_dcache_mmap_lock_irqsave(mapping, flags)		\
+		xa_lock_irqsave(&mapping->i_pages, flags)
+#define flush_dcache_mmap_unlock_irqrestore(mapping, flags)	\
+		xa_unlock_irqrestore(&mapping->i_pages, flags)

 #endif /* _ASM_NIOS2_CACHEFLUSH_H */
diff --git a/arch/nios2/mm/cacheflush.c b/arch/nios2/mm/cacheflush.c
index 6aa9257c3ede..35f3b599187f 100644
=2D-- a/arch/nios2/mm/cacheflush.c
+++ b/arch/nios2/mm/cacheflush.c
@@ -75,11 +75,12 @@ static void flush_aliases(struct address_space *mappin=
g, struct page *page)
 {
 	struct mm_struct *mm =3D current->active_mm;
 	struct vm_area_struct *mpnt;
+	unsigned long flags;
 	pgoff_t pgoff;

 	pgoff =3D page->index;

-	flush_dcache_mmap_lock(mapping);
+	flush_dcache_mmap_lock_irqsave(mapping, flags);
 	vma_interval_tree_foreach(mpnt, &mapping->i_mmap, pgoff, pgoff) {
 		unsigned long offset;

@@ -92,7 +93,7 @@ static void flush_aliases(struct address_space *mapping,=
 struct page *page)
 		flush_cache_page(mpnt, mpnt->vm_start + offset,
 			page_to_pfn(page));
 	}
-	flush_dcache_mmap_unlock(mapping);
+	flush_dcache_mmap_unlock_irqrestore(mapping, flags);
 }

 void flush_cache_all(void)
=2D-
2.38.1