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Groups > linux.kernel > #1664420

[PATCH v6 16/18] mtd: nand: denali: use non-managed kmalloc() for DMA buffer

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As Russell and Lars stated in the discussion [1], using
devm_k*alloc() with DMA is not a good idea.

Let's use kmalloc (not kzalloc because no need for zero-out).
Also, allocate the buffer as late as possible because it must be
freed for any error that follows.

[1] https://lkml.org/lkml/2017/3/8/693

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Cc: Russell King <rmk+kernel@armlinux.org.uk>
Cc: Lars-Peter Clausen <lars@metafoo.de>
Acked-by: Robin Murphy <robin.murphy@arm.com>
---

Changes in v6: None
Changes in v5: None
Changes in v4: None
Changes in v3: None
Changes in v2:
  - Newly added

 drivers/mtd/nand/denali.c | 26 +++++++++++++++++---------
 1 file changed, 17 insertions(+), 9 deletions(-)

diff --git a/drivers/mtd/nand/denali.c b/drivers/mtd/nand/denali.c
index 918b9b9bbe53..d37fb82f39ed 100644
--- a/drivers/mtd/nand/denali.c
+++ b/drivers/mtd/nand/denali.c
@@ -23,6 +23,7 @@
 #include <linux/mutex.h>
 #include <linux/mtd/mtd.h>
 #include <linux/module.h>
+#include <linux/slab.h>
 
 #include "denali.h"
 
@@ -1343,13 +1344,6 @@ int denali_init(struct denali_nand_info *denali)
 	if (ret)
 		goto disable_irq;
 
-	denali->buf = devm_kzalloc(denali->dev, mtd->writesize + mtd->oobsize,
-				   GFP_KERNEL);
-	if (!denali->buf) {
-		ret = -ENOMEM;
-		goto disable_irq;
-	}
-
 	if (ioread32(denali->flash_reg + FEATURES) & FEATURES__DMA)
 		denali->dma_avail = 1;
 
@@ -1434,17 +1428,30 @@ int denali_init(struct denali_nand_info *denali)
 	if (ret)
 		goto disable_irq;
 
+	/*
+	 * This buffer is DMA-mapped by denali_{read,write}_page_raw.  Do not
+	 * use devm_kmalloc() because the memory allocated by devm_ does not
+	 * guarantee DMA-safe alignment.
+	 */
+	denali->buf = kmalloc(mtd->writesize + mtd->oobsize, GFP_KERNEL);
+	if (!denali->buf) {
+		ret = -ENOMEM;
+		goto disable_irq;
+	}
+
 	ret = nand_scan_tail(mtd);
 	if (ret)
-		goto disable_irq;
+		goto free_buf;
 
 	ret = mtd_device_register(mtd, NULL, 0);
 	if (ret) {
 		dev_err(denali->dev, "Failed to register MTD: %d\n", ret);
-		goto disable_irq;
+		goto free_buf;
 	}
 	return 0;
 
+free_buf:
+	kfree(denali->buf);
 disable_irq:
 	denali_disable_irq(denali);
 
@@ -1458,6 +1465,7 @@ void denali_remove(struct denali_nand_info *denali)
 	struct mtd_info *mtd = nand_to_mtd(&denali->nand);
 
 	nand_release(mtd);
+	kfree(denali->buf);
 	denali_disable_irq(denali);
 }
 EXPORT_SYMBOL(denali_remove);
-- 
2.7.4

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[PATCH v6 00/18] mtd: nand: denali: Denali NAND IP patch bomb Masahiro Yamada <yamada.masahiro@socionext.com> - 2017-06-13 07:10 +0200
  [PATCH v6 02/18] mtd: nand: denali: remove unneeded find_valid_banks() Masahiro Yamada <yamada.masahiro@socionext.com> - 2017-06-13 07:10 +0200
  [PATCH v6 08/18] mtd: nand: denali: fix bank reset function to detect the number of chips Masahiro Yamada <yamada.masahiro@socionext.com> - 2017-06-13 07:10 +0200
  [PATCH v6 01/18] mtd: nand: denali: set NAND_ECC_CUSTOM_PAGE_ACCESS Masahiro Yamada <yamada.masahiro@socionext.com> - 2017-06-13 07:10 +0200
  [PATCH v6 16/18] mtd: nand: denali: use non-managed kmalloc() for DMA buffer Masahiro Yamada <yamada.masahiro@socionext.com> - 2017-06-13 07:10 +0200
  [PATCH v6 09/18] mtd: nand: denali: use interrupt instead of polling for bank reset Masahiro Yamada <yamada.masahiro@socionext.com> - 2017-06-13 07:10 +0200
  [PATCH v6 07/18] mtd: nand: denali: switch over to cmd_ctrl instead of cmdfunc Masahiro Yamada <yamada.masahiro@socionext.com> - 2017-06-13 07:10 +0200
  [PATCH v6 05/18] mtd: nand: denali: fix NAND_CMD_STATUS handling Masahiro Yamada <yamada.masahiro@socionext.com> - 2017-06-13 07:10 +0200
  [PATCH v6 18/18] mtd: nand: denali: avoid magic numbers and rename for clarification Masahiro Yamada <yamada.masahiro@socionext.com> - 2017-06-13 07:10 +0200
  [PATCH v6 15/18] mtd: nand: denali: skip driver internal bounce buffer when possible Masahiro Yamada <yamada.masahiro@socionext.com> - 2017-06-13 07:10 +0200
  [PATCH v6 03/18] mtd: nand: denali: handle timing parameters by setup_data_interface() Masahiro Yamada <yamada.masahiro@socionext.com> - 2017-06-13 07:10 +0200
  [PATCH v6 06/18] mtd: nand: denali: fix NAND_CMD_PARAM handling Masahiro Yamada <yamada.masahiro@socionext.com> - 2017-06-13 07:10 +0200
  [PATCH v6 13/18] mtd: nand: denali: fix raw and oob accessors for syndrome page layout Masahiro Yamada <yamada.masahiro@socionext.com> - 2017-06-13 07:10 +0200
  [PATCH v6 17/18] mtd: nand: denali: enable bad block table scan Masahiro Yamada <yamada.masahiro@socionext.com> - 2017-06-13 07:10 +0200
  [PATCH v6 11/18] mtd: nand: denali: merge struct nand_buf into struct denali_nand_info Masahiro Yamada <yamada.masahiro@socionext.com> - 2017-06-13 07:10 +0200
  [PATCH v6 14/18] mtd: nand: denali: support hardware-assisted erased page detection Masahiro Yamada <yamada.masahiro@socionext.com> - 2017-06-13 07:10 +0200
  [PATCH v6 12/18] mtd: nand: denali: use flag instead of register macro for direction Masahiro Yamada <yamada.masahiro@socionext.com> - 2017-06-13 07:20 +0200
  [PATCH v6 04/18] mtd: nand: denali: rework interrupt handling Masahiro Yamada <yamada.masahiro@socionext.com> - 2017-06-13 07:20 +0200
  [PATCH v6 10/18] mtd: nand: denali: propagate page to helpers via function argument Masahiro Yamada <yamada.masahiro@socionext.com> - 2017-06-13 07:20 +0200
  Re: [PATCH v6 00/18] mtd: nand: denali: Denali NAND IP patch bomb Boris Brezillon <boris.brezillon@free-electrons.com> - 2017-06-13 09:10 +0200
    Re: [PATCH v6 00/18] mtd: nand: denali: Denali NAND IP patch bomb Masahiro Yamada <yamada.masahiro@socionext.com> - 2017-06-13 10:10 +0200
      Re: [PATCH v6 00/18] mtd: nand: denali: Denali NAND IP patch bomb Boris Brezillon <boris.brezillon@free-electrons.com> - 2017-06-13 10:30 +0200
    Re: [PATCH v6 00/18] mtd: nand: denali: Denali NAND IP patch bomb Masahiro Yamada <yamada.masahiro@socionext.com> - 2017-06-13 10:20 +0200
      Re: [PATCH v6 00/18] mtd: nand: denali: Denali NAND IP patch bomb Boris Brezillon <boris.brezillon@free-electrons.com> - 2017-06-13 10:40 +0200
        Re: [PATCH v6 00/18] mtd: nand: denali: Denali NAND IP patch bomb Masahiro Yamada <yamada.masahiro@socionext.com> - 2017-06-13 11:00 +0200

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