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Message-ID: <06f83492-1eaf-16c4-31b0-1f148995ee59@cybernetics.com>
Date: Tue, 7 Jun 2022 14:44:18 -0400
From: Tony Battersby <tonyb@...ernetics.com>
To: linux-mm@...ck.org, linux-kernel@...r.kernel.org
Cc: iommu@...ts.linux-foundation.org, kernel-team@...com,
Matthew Wilcox <willy@...radead.org>,
Keith Busch <kbusch@...nel.org>,
Andy Shevchenko <andy.shevchenko@...il.com>,
Robin Murphy <robin.murphy@....com>,
Tony Lindgren <tony@...mide.com>
Subject: [PATCH v6 07/11] dmapool: ignore init_on_free when DMAPOOL_DEBUG
enabled
There are two cases:
1) In the normal case that the memory is being freed correctly, then
DMAPOOL_DEBUG will memset the memory anyway, so speed thing up by
avoiding a double-memset of the same memory.
2) In the abnormal case that DMAPOOL_DEBUG detects that a driver passes
incorrect parameters to dma_pool_free() (e.g. double-free, invalid
free, mismatched vaddr/dma, etc.), then that is a kernel bug, and we
don't want to clear the passed-in possibly-invalid memory pointer
because we can't be sure that the memory is really free. So don't clear
it just because init_on_free=1.
Signed-off-by: Tony Battersby <tonyb@...ernetics.com>
---
mm/dmapool.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)
diff --git a/mm/dmapool.c b/mm/dmapool.c
index facdb3571976..44038089a41a 100644
--- a/mm/dmapool.c
+++ b/mm/dmapool.c
@@ -406,8 +406,6 @@ void dma_pool_free(struct dma_pool *pool, void *vaddr, dma_addr_t dma)
}
offset = vaddr - page->vaddr;
- if (want_init_on_free())
- memset(vaddr, 0, pool->size);
#ifdef DMAPOOL_DEBUG
if ((dma - page->dma) != offset) {
spin_unlock_irqrestore(&pool->lock, flags);
@@ -452,6 +450,9 @@ void dma_pool_free(struct dma_pool *pool, void *vaddr, dma_addr_t dma)
goto freelist_corrupt;
}
memset(vaddr, POOL_POISON_FREED, pool->size);
+#else
+ if (want_init_on_free())
+ memset(vaddr, 0, pool->size);
#endif
page->in_use--;
--
2.25.1
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