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GET /api/1.2/patches/810816/?format=api
HTTP 200 OK
Allow: GET, PUT, PATCH, HEAD, OPTIONS
Content-Type: application/json
Vary: Accept

{
    "id": 810816,
    "url": "http://patchwork.ozlabs.org/api/1.2/patches/810816/?format=api",
    "web_url": "http://patchwork.ozlabs.org/project/linux-mtd/patch/20170906214502.26748-1-cyrille.pitchen@wedev4u.fr/",
    "project": {
        "id": 3,
        "url": "http://patchwork.ozlabs.org/api/1.2/projects/3/?format=api",
        "name": "Linux MTD development",
        "link_name": "linux-mtd",
        "list_id": "linux-mtd.lists.infradead.org",
        "list_email": "linux-mtd@lists.infradead.org",
        "web_url": null,
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        "webscm_url": null,
        "list_archive_url": "",
        "list_archive_url_format": "",
        "commit_url_format": ""
    },
    "msgid": "<20170906214502.26748-1-cyrille.pitchen@wedev4u.fr>",
    "list_archive_url": null,
    "date": "2017-09-06T21:45:02",
    "name": "mtd: spi-nor: fix DMA unsafe buffer issue in spi_nor_read_sfdp()",
    "commit_ref": null,
    "pull_url": null,
    "state": "accepted",
    "archived": false,
    "hash": "d176dc91fc64ea2476106eabe54f30f8a98cfeb4",
    "submitter": {
        "id": 70551,
        "url": "http://patchwork.ozlabs.org/api/1.2/people/70551/?format=api",
        "name": "Cyrille Pitchen",
        "email": "cyrille.pitchen@wedev4u.fr"
    },
    "delegate": {
        "id": 58324,
        "url": "http://patchwork.ozlabs.org/api/1.2/users/58324/?format=api",
        "username": "bbrezillon",
        "first_name": "Boris",
        "last_name": "Brezillon",
        "email": "boris.brezillon@free-electrons.com"
    },
    "mbox": "http://patchwork.ozlabs.org/project/linux-mtd/patch/20170906214502.26748-1-cyrille.pitchen@wedev4u.fr/mbox/",
    "series": [
        {
            "id": 1890,
            "url": "http://patchwork.ozlabs.org/api/1.2/series/1890/?format=api",
            "web_url": "http://patchwork.ozlabs.org/project/linux-mtd/list/?series=1890",
            "date": "2017-09-06T21:45:02",
            "name": "mtd: spi-nor: fix DMA unsafe buffer issue in spi_nor_read_sfdp()",
            "version": 1,
            "mbox": "http://patchwork.ozlabs.org/series/1890/mbox/"
        }
    ],
    "comments": "http://patchwork.ozlabs.org/api/patches/810816/comments/",
    "check": "pending",
    "checks": "http://patchwork.ozlabs.org/api/patches/810816/checks/",
    "tags": {},
    "related": [],
    "headers": {
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        "From": "Cyrille Pitchen <cyrille.pitchen@wedev4u.fr>",
        "To": "marek.vasut@gmail.com, linux-mtd@lists.infradead.org,\n\tgeert@linux-m68k.org",
        "Subject": "[PATCH] mtd: spi-nor: fix DMA unsafe buffer issue in\n\tspi_nor_read_sfdp()",
        "Date": "Wed,  6 Sep 2017 23:45:02 +0200",
        "Message-Id": "<20170906214502.26748-1-cyrille.pitchen@wedev4u.fr>",
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        "Cc": "boris.brezillon@free-electrons.com, richard@nod.at,\n\tlinux-kernel@vger.kernel.org,\n\tCyrille Pitchen <cyrille.pitchen@wedev4u.fr>, \n\tcomputersforpeace@gmail.com, dwmw2@infradead.org",
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    },
    "content": "spi_nor_read_sfdp() calls nor->read() to read the SFDP data.\nWhen the m25p80 driver is used (pretty common case), nor->read() is then\nimplemented by the m25p80_read() function, which is likely to initialize a\n'struct spi_transfer' from its buf argument before appending this\nstructure inside the 'struct spi_message' argument of spi_sync().\n\nBesides the SPI sub-system states that both .tx_buf and .rx_buf members of\n'struct spi_transfer' must point into dma-safe memory. However, two of the\nthree calls of spi_nor_read_sfdp() were given pointers to stack allocated\nmemory as buf argument, hence not in a dma-safe area.\nHopefully, the third and last call of spi_nor_read_sfdp() was already\ngiven a kmalloc'ed buffer argument, hence dma-safe.\n\nSo this patch fixes this issue by introducing a\nspi_nor_read_sfdp_dma_unsafe() function which simply wraps the existing\nspi_nor_read_sfdp() function and uses some kmalloc'ed memory as a bounce\nbuffer.\n\nReported-by: Geert Uytterhoeven <geert@linux-m68k.org>\nSigned-off-by: Cyrille Pitchen <cyrille.pitchen@wedev4u.fr>\n---\n\nCompiled but not tested yet!\n\n drivers/mtd/spi-nor/spi-nor.c | 36 +++++++++++++++++++++++++++++++++---\n 1 file changed, 33 insertions(+), 3 deletions(-)",
    "diff": "diff --git a/drivers/mtd/spi-nor/spi-nor.c b/drivers/mtd/spi-nor/spi-nor.c\nindex cf1d4a15e10a..05254dd6a4a0 100644\n--- a/drivers/mtd/spi-nor/spi-nor.c\n+++ b/drivers/mtd/spi-nor/spi-nor.c\n@@ -1784,7 +1784,7 @@ spi_nor_set_pp_settings(struct spi_nor_pp_command *pp,\n  * @nor:\tpointer to a 'struct spi_nor'\n  * @addr:\toffset in the SFDP area to start reading data from\n  * @len:\tnumber of bytes to read\n- * @buf:\tbuffer where the SFDP data are copied into\n+ * @buf:\tbuffer where the SFDP data are copied into (dma-safe memory)\n  *\n  * Whatever the actual numbers of bytes for address and dummy cycles are\n  * for (Fast) Read commands, the Read SFDP (5Ah) instruction is always\n@@ -1829,6 +1829,36 @@ static int spi_nor_read_sfdp(struct spi_nor *nor, u32 addr,\n \treturn ret;\n }\n \n+/**\n+ * spi_nor_read_sfdp_dma_unsafe() - read Serial Flash Discoverable Parameters.\n+ * @nor:\tpointer to a 'struct spi_nor'\n+ * @addr:\toffset in the SFDP area to start reading data from\n+ * @len:\tnumber of bytes to read\n+ * @buf:\tbuffer where the SFDP data are copied into\n+ *\n+ * Wrap spi_nor_read_sfdp() using a kmalloc'ed bounce buffer as @buf is now not\n+ * guaranteed to be dma-safe.\n+ *\n+ * Return: -ENOMEM if kmalloc() fails, the return code of spi_nor_read_sfdp()\n+ *          otherwise.\n+ */\n+static int spi_nor_read_sfdp_dma_unsafe(struct spi_nor *nor, u32 addr,\n+\t\t\t\t\tsize_t len, void *buf)\n+{\n+\tvoid *dma_safe_buf;\n+\tint ret;\n+\n+\tdma_safe_buf = kmalloc(len, GFP_KERNEL);\n+\tif (!dma_safe_buf)\n+\t\treturn -ENOMEM;\n+\n+\tret = spi_nor_read_sfdp(nor, addr, len, dma_safe_buf);\n+\tmemcpy(buf, dma_safe_buf, len);\n+\tkfree(dma_safe_buf);\n+\n+\treturn ret;\n+}\n+\n struct sfdp_parameter_header {\n \tu8\t\tid_lsb;\n \tu8\t\tminor;\n@@ -2101,7 +2131,7 @@ static int spi_nor_parse_bfpt(struct spi_nor *nor,\n \t\t    bfpt_header->length * sizeof(u32));\n \taddr = SFDP_PARAM_HEADER_PTP(bfpt_header);\n \tmemset(&bfpt, 0, sizeof(bfpt));\n-\terr = spi_nor_read_sfdp(nor,  addr, len, &bfpt);\n+\terr = spi_nor_read_sfdp_dma_unsafe(nor,  addr, len, &bfpt);\n \tif (err < 0)\n \t\treturn err;\n \n@@ -2243,7 +2273,7 @@ static int spi_nor_parse_sfdp(struct spi_nor *nor,\n \tint i, err;\n \n \t/* Get the SFDP header. */\n-\terr = spi_nor_read_sfdp(nor, 0, sizeof(header), &header);\n+\terr = spi_nor_read_sfdp_dma_unsafe(nor, 0, sizeof(header), &header);\n \tif (err < 0)\n \t\treturn err;\n \n",
    "prefixes": []
}