Re:Re: [PATCH RESEND,v3,4/4] drivers: uio: new driver for fsl_85xx_cache_sram

Hi, Christophe,
dev_kzalloc really looks better. I will update the patch with the comments addressed.

Thanks,
Wenhu

From: Christophe Leroy <redacted> Date: 2020-04-16 19:49:01
To:Wang Wenhu [off-list ref],gregkh@linuxfoundation.org,
linux-kernel@vger.kernel.org,oss@buserror.net,linuxppc-dev@lists.ozlabs.org
 cc: kernel@vivo.com,Michael Ellerman [off-list ref]
Subject: Re: [PATCH RESEND,v3,4/4] drivers: uio: new driver for fsl_85xx_cache_sram>

Le 16/04/2020 à 13:16, Wang Wenhu a écrit :

quoted

A driver for freescale 85xx platforms to access the Cache-Sram form
user level. This is extremely helpful for some user-space applications
that require high performance memory accesses.

Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Christophe Leroy <redacted>
Cc: Scott Wood <oss@buserror.net>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: linuxppc-dev@lists.ozlabs.org
Signed-off-by: Wang Wenhu <redacted>
---
Changes since v1:
  * Addressed comments from Greg K-H
  * Moved kfree(info->name) into uio_info_free_internal()
Changes since v2:
  * Addressed comments from Greg, Scott and Christophe
  * Use "uiomem->internal_addr" as if condition for sram memory free,
    and memset the uiomem entry
  * Modified of_match_table make the driver apart from Cache-Sram HW info
    which belong to the HW level driver fsl_85xx_cache_sram to match
  * Use roundup_pow_of_two for align calculation
  * Remove useless clear block of uiomem entries.
  * Use UIO_INFO_VER micro for info->version, and define it as
    "devicetree,pseudo", meaning this is pseudo device and probed from
    device tree configuration
  * Select FSL_85XX_CACHE_SRAM rather than depends on it
---
  drivers/uio/Kconfig                   |   9 ++
  drivers/uio/Makefile                  |   1 +
  drivers/uio/uio_fsl_85xx_cache_sram.c | 158 ++++++++++++++++++++++++++
  3 files changed, 168 insertions(+)
  create mode 100644 drivers/uio/uio_fsl_85xx_cache_sram.c

diff --git a/drivers/uio/Kconfig b/drivers/uio/Kconfig
index 202ee81cfc2b..9c3b47461b71 100644
--- a/drivers/uio/Kconfig
+++ b/drivers/uio/Kconfig

@@ -105,6 +105,15 @@ config UIO_NETX
  	  To compile this driver as a module, choose M here; the module
  	  will be called uio_netx.
  
+config UIO_FSL_85XX_CACHE_SRAM
+	tristate "Freescale 85xx Cache-Sram driver"
+	depends on FSL_SOC_BOOKE && PPC32
+	select FSL_85XX_CACHE_SRAM
+	help
+	  Generic driver for accessing the Cache-Sram form user level. This
+	  is extremely helpful for some user-space applications that require
+	  high performance memory accesses.
+
  config UIO_FSL_ELBC_GPCM
  	tristate "eLBC/GPCM driver"
  	depends on FSL_LBC

diff --git a/drivers/uio/Makefile b/drivers/uio/Makefile
index c285dd2a4539..be2056cffc21 100644
--- a/drivers/uio/Makefile
+++ b/drivers/uio/Makefile

@@ -10,4 +10,5 @@ obj-$(CONFIG_UIO_NETX)	+= uio_netx.o
  obj-$(CONFIG_UIO_PRUSS)         += uio_pruss.o
  obj-$(CONFIG_UIO_MF624)         += uio_mf624.o
  obj-$(CONFIG_UIO_FSL_ELBC_GPCM)	+= uio_fsl_elbc_gpcm.o
+obj-$(CONFIG_UIO_FSL_85XX_CACHE_SRAM)	+= uio_fsl_85xx_cache_sram.o
  obj-$(CONFIG_UIO_HV_GENERIC)	+= uio_hv_generic.o

diff --git a/drivers/uio/uio_fsl_85xx_cache_sram.c b/drivers/uio/uio_fsl_85xx_cache_sram.c
new file mode 100644
index 000000000000..8701df695307
--- /dev/null
+++ b/drivers/uio/uio_fsl_85xx_cache_sram.c

@@ -0,0 +1,158 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2020 Vivo Communication Technology Co. Ltd.
+ * Copyright (C) 2020 Wang Wenhu <wenhu.wang@vivo.com>
+ * All rights reserved.
+ */
+
+#include <linux/platform_device.h>
+#include <linux/uio_driver.h>
+#include <linux/stringify.h>
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <asm/fsl_85xx_cache_sram.h>
+
+#define DRIVER_NAME	"uio_fsl_85xx_cache_sram"
+#define UIO_INFO_VER	"devicetree,pseudo"
+#define UIO_NAME	"uio_cache_sram"
+
+static void uio_info_free_internal(struct uio_info *info)
+{
+	struct uio_mem *uiomem = info->mem;
+
+	while (uiomem < &info->mem[MAX_UIO_MAPS]) {

As suggested by Scott, maybe it would be better to use a loop with an 
index, something like

for (i = 0; i < MAX_UIO_MAPS; i++, uiomem++) {
	struct uio_mem *uiomem = info->mem[i];

quoted

+		if (uiomem->internal_addr) {
+			mpc85xx_cache_sram_free(uiomem->internal_addr);
+			kfree(uiomem->name);

Unneeded when using devm_kstrdup(), see in the probe function.

quoted

+			memset(uiomem, 0, sizeof(*uiomem));
+		}
+		uiomem++;
+	}
+
+	kfree(info->name);

That's a bit unbalanced. This function is handy for the things allocated 
inside the loop, but for the info->name allocated outside the loop, it 
should be released outside this function.

At the end if you use devm_kstrdup(), it will void anyway.

quoted

+}
+
+static int uio_fsl_85xx_cache_sram_probe(struct platform_device *pdev)
+{
+	struct device_node *parent = pdev->dev.of_node;
+	struct device_node *node = NULL;
+	struct uio_info *info;
+	struct uio_mem *uiomem;
+	const char *dt_name;
+	u32 mem_size;
+	int ret;
+
+	/* alloc uio_info for one device */
+	info = kzalloc(sizeof(*info), GFP_KERNEL);

Maybe use devm_kzalloc(). That way, it will be automatically freed when 
the driver is released, both a normal release and on probe failure.

quoted

+	if (!info)
+		return -ENOMEM;
+
+	/* get optional uio name */
+	if (of_property_read_string(parent, "uio_name", &dt_name))
+		dt_name = UIO_NAME;
+
+	info->name = kstrdup(dt_name, GFP_KERNEL);

Can use devm_kstrdup()

quoted

+	if (!info->name) {
+		ret = -ENOMEM;

If using devm_kzalloc(), you can then directly do return -ENOMEM, and 
the release will be automatic.

quoted

+		goto err_info_free;
+	}
+
+	uiomem = info->mem;
+	for_each_child_of_node(parent, node) {
+		void *virt;
+		phys_addr_t phys;
+
+		ret = of_property_read_u32(node, "cache-mem-size", &mem_size);
+		if (ret) {
+			ret = -EINVAL;
+			goto err_info_free_internal;
+		}
+
+		if (mem_size == 0) {
+			dev_err(&pdev->dev, "cache-mem-size should not be 0\n");
+			ret = -EINVAL;
+			goto err_info_free_internal;
+		}
+
+		virt = mpc85xx_cache_sram_alloc(mem_size,
+						&phys,

I think &phys can fit on first line.

quoted

+						roundup_pow_of_two(mem_size));
+		if (!virt) {
+			/* mpc85xx_cache_sram_alloc to define the real cause */
+			ret = -ENOMEM;
+			goto err_info_free_internal;
+		}
+
+		uiomem->memtype = UIO_MEM_PHYS;
+		uiomem->addr = phys;
+		uiomem->size = mem_size;
+		uiomem->name = kstrdup(node->name, GFP_KERNEL);;

Use devm_kstrdup()

quoted

+		uiomem->internal_addr = virt;
+		uiomem++;
+
+		if (uiomem >= &info->mem[MAX_UIO_MAPS]) {
+			dev_warn(&pdev->dev, "more than %d uio-maps for device.\n",
+				 MAX_UIO_MAPS);
+			break;
+		}
+	}
+
+	if (uiomem == info->mem) {
+		dev_err(&pdev->dev, "error no valid uio-map configured\n");
+		ret = -EINVAL;
+		goto err_info_free_internal;

Is there anything to free up if nothing has been allocated ?

quoted

+	}
+
+	info->version = UIO_INFO_VER;
+
+	/* register uio device */
+	if (uio_register_device(&pdev->dev, info)) {
+		dev_err(&pdev->dev, "uio registration failed\n");
+		ret = -ENODEV;
+		goto err_info_free_internal;
+	}
+
+	platform_set_drvdata(pdev, info);
+
+	return 0;
+err_info_free_internal:
+	uio_info_free_internal(info);
+err_info_free:
+	kfree(info);

Shouldn't be needed when using devm_kzalloc().

quoted

+	return ret;
+}
+
+static int uio_fsl_85xx_cache_sram_remove(struct platform_device *pdev)
+{
+	struct uio_info *info = platform_get_drvdata(pdev);
+
+	uio_unregister_device(info);
+
+	uio_info_free_internal(info);
+
+	kfree(info);

Not needed when using dev_kzalloc()

quoted

+
+	return 0;
+}
+
+static const struct of_device_id uio_mpc85xx_l2ctlr_of_match[] = {
+	{	.compatible = "uio,mpc85xx-cache-sram",	},
+	{},
+};
+
+static struct platform_driver uio_fsl_85xx_cache_sram = {
+	.probe = uio_fsl_85xx_cache_sram_probe,
+	.remove = uio_fsl_85xx_cache_sram_remove,
+	.driver = {
+		.name = DRIVER_NAME,
+		.owner = THIS_MODULE,
+		.of_match_table	= uio_mpc85xx_l2ctlr_of_match,
+	},
+};
+
+module_platform_driver(uio_fsl_85xx_cache_sram);
+
+MODULE_AUTHOR("Wang Wenhu [off-list ref]");
+MODULE_DESCRIPTION("Freescale MPC85xx Cache-Sram UIO Platform Driver");
+MODULE_ALIAS("platform:" DRIVER_NAME);
+MODULE_LICENSE("GPL v2");

Christophe