[PATCH v4 1/2] remoteproc: Add remoteproc character device interface
Bjorn Andersson
bjorn.andersson at linaro.org
Fri Jul 17 01:46:15 EDT 2020
On Wed 15 Jul 13:18 PDT 2020, Mathieu Poirier wrote:
> On Tue, Jul 07, 2020 at 12:07:49PM -0700, Siddharth Gupta wrote:
> > Add the character device interface into remoteproc framework.
> > This interface can be used in order to boot/shutdown remote
> > subsystems and provides a basic ioctl based interface to implement
> > supplementary functionality. An ioctl call is implemented to enable
> > the shutdown on release feature which will allow remote processors to
> > be shutdown when the controlling userpsace application crashes or hangs.
> >
> > Signed-off-by: Rishabh Bhatnagar <rishabhb at codeaurora.org>
> > Signed-off-by: Siddharth Gupta <sidgup at codeaurora.org>
> > ---
> > Documentation/userspace-api/ioctl/ioctl-number.rst | 1 +
> > drivers/remoteproc/Kconfig | 9 ++
> > drivers/remoteproc/Makefile | 1 +
> > drivers/remoteproc/remoteproc_cdev.c | 146 +++++++++++++++++++++
> > drivers/remoteproc/remoteproc_internal.h | 28 ++++
> > include/linux/remoteproc.h | 5 +
> > include/uapi/linux/remoteproc_cdev.h | 37 ++++++
> > 7 files changed, 227 insertions(+)
> > create mode 100644 drivers/remoteproc/remoteproc_cdev.c
> > create mode 100644 include/uapi/linux/remoteproc_cdev.h
> >
> > diff --git a/Documentation/userspace-api/ioctl/ioctl-number.rst b/Documentation/userspace-api/ioctl/ioctl-number.rst
> > index 59472cd..2a19883 100644
> > --- a/Documentation/userspace-api/ioctl/ioctl-number.rst
> > +++ b/Documentation/userspace-api/ioctl/ioctl-number.rst
> > @@ -339,6 +339,7 @@ Code Seq# Include File Comments
> > 0xB4 00-0F linux/gpio.h <mailto:linux-gpio at vger.kernel.org>
> > 0xB5 00-0F uapi/linux/rpmsg.h <mailto:linux-remoteproc at vger.kernel.org>
> > 0xB6 all linux/fpga-dfl.h
> > +0xB7 all uapi/linux/remoteproc_cdev.h <mailto:linux-remoteproc at vger.kernel.org>
> > 0xC0 00-0F linux/usb/iowarrior.h
> > 0xCA 00-0F uapi/misc/cxl.h
> > 0xCA 10-2F uapi/misc/ocxl.h
> > diff --git a/drivers/remoteproc/Kconfig b/drivers/remoteproc/Kconfig
> > index c4d1731..652060f 100644
> > --- a/drivers/remoteproc/Kconfig
> > +++ b/drivers/remoteproc/Kconfig
> > @@ -14,6 +14,15 @@ config REMOTEPROC
> >
> > if REMOTEPROC
> >
> > +config REMOTEPROC_CDEV
> > + bool "Remoteproc character device interface"
> > + help
> > + Say y here to have a character device interface for the remoteproc
> > + framework. Userspace can boot/shutdown remote processors through
> > + this interface.
> > +
> > + It's safe to say N if you don't want to use this interface.
> > +
> > config IMX_REMOTEPROC
> > tristate "IMX6/7 remoteproc support"
> > depends on ARCH_MXC
> > diff --git a/drivers/remoteproc/Makefile b/drivers/remoteproc/Makefile
> > index e8b886e..311ae3f 100644
> > --- a/drivers/remoteproc/Makefile
> > +++ b/drivers/remoteproc/Makefile
> > @@ -9,6 +9,7 @@ remoteproc-y += remoteproc_debugfs.o
> > remoteproc-y += remoteproc_sysfs.o
> > remoteproc-y += remoteproc_virtio.o
> > remoteproc-y += remoteproc_elf_loader.o
> > +obj-$(CONFIG_REMOTEPROC_CDEV) += remoteproc_cdev.o
> > obj-$(CONFIG_IMX_REMOTEPROC) += imx_rproc.o
> > obj-$(CONFIG_INGENIC_VPU_RPROC) += ingenic_rproc.o
> > obj-$(CONFIG_MTK_SCP) += mtk_scp.o mtk_scp_ipi.o
> > diff --git a/drivers/remoteproc/remoteproc_cdev.c b/drivers/remoteproc/remoteproc_cdev.c
> > new file mode 100644
> > index 0000000..8a0eb47
> > --- /dev/null
> > +++ b/drivers/remoteproc/remoteproc_cdev.c
> > @@ -0,0 +1,146 @@
> > +// SPDX-License-Identifier: GPL-2.0-only
> > +/*
> > + * Character device interface driver for Remoteproc framework.
> > + *
> > + * Copyright (c) 2020, The Linux Foundation. All rights reserved.
> > + */
> > +
> > +#include <linux/cdev.h>
> > +#include <linux/fs.h>
> > +#include <linux/module.h>
> > +#include <linux/mutex.h>
> > +#include <linux/compat.h>
> > +#include <linux/remoteproc.h>
> > +#include <linux/uaccess.h>
> > +#include <uapi/linux/remoteproc_cdev.h>
>
> Alphabetical order please.
>
> > +
> > +#include "remoteproc_internal.h"
> > +
> > +#define NUM_RPROC_DEVICES 64
> > +static dev_t rproc_major;
> > +
> > +static ssize_t rproc_cdev_write(struct file *filp, const char __user *buf, size_t len, loff_t *pos)
> > +{
> > + struct rproc *rproc = container_of(filp->f_inode->i_cdev, struct rproc, char_dev);
> > + int ret = 0;
> > + char cmd[10];
> > +
> > + if (!len || len > sizeof(cmd))
> > + return -EINVAL;
> > +
> > + ret = copy_from_user(cmd, buf, sizeof(cmd));
> > + if (ret)
> > + return -EFAULT;
> > +
> > + if (sysfs_streq(cmd, "start")) {
> > + if (rproc->state == RPROC_RUNNING)
> > + return -EBUSY;
> > +
> > + ret = rproc_boot(rproc);
> > + if (ret)
> > + dev_err(&rproc->dev, "Boot failed:%d\n", ret);
> > + } else if (sysfs_streq(cmd, "stop")) {
> > + if (rproc->state != RPROC_RUNNING)
> > + return -EINVAL;
> > +
> > + rproc_shutdown(rproc);
> > + } else {
> > + dev_err(&rproc->dev, "Unrecognized option\n");
> > + ret = -EINVAL;
> > + }
> > +
> > + return ret ? ret : len;
> > +}
> > +
> > +static long rproc_device_ioctl(struct file *filp, unsigned int ioctl, unsigned long arg)
> > +{
> > + struct rproc *rproc = container_of(filp->f_inode->i_cdev, struct rproc, char_dev);
> > + void __user *argp = compat_ptr(arg);
> > + int ret;
> > + int32_t param;
> > +
> > + switch (ioctl) {
> > + case RPROC_SET_SHUTDOWN_ON_RELEASE:
> > + ret = copy_from_user(¶m, argp, sizeof(int32_t));
> > + if (ret) {
> > + dev_err(&rproc->dev, "Data copy from userspace failed\n");
> > + return -EFAULT;
> > + }
> > + mutex_lock(&rproc->lock);
> > + rproc->cdev_put_on_release = param ? true : false;
> > + mutex_unlock(&rproc->lock);
> > + break;
> > + case RPROC_GET_SHUTDOWN_ON_RELEASE:
> > + mutex_lock(&rproc->lock);
> > + ret = copy_to_user(argp, &rproc->cdev_put_on_release, sizeof(bool));
> > + mutex_unlock(&rproc->lock);
> > + if (ret) {
> > + dev_err(&rproc->dev, "Data copy to userspace failed\n");
> > + return -EFAULT;
> > + }
> > + break;
> > + default:
> > + dev_err(&rproc->dev, "Unsupported ioctl\n");
> > + return -EINVAL;
> > + }
> > +
> > + return 0;
> > +}
> > +
> > +static int rproc_cdev_release(struct inode *inode, struct file *filp)
> > +{
> > + struct rproc *rproc = container_of(inode->i_cdev, struct rproc, char_dev);
> > + bool release;
> > +
> > + mutex_lock(&rproc->lock);
> > + release = rproc->cdev_put_on_release;
> > + mutex_unlock(&rproc->lock);
> > +
> > + if (release && rproc->state == RPROC_RUNNING)
>
> I think the state of the processor should also be acquired when the lock is
> held. There is still a chance ->state can change between the time the lock is
> released and rproc_shutdown() is called but that's a known problem for which
> patches have been sent out.
>
There where patches for a similar bug in the debugfs interface, but I'm
not able to find anything for rproc_shutdown().
As I suggested in the previous version of this series I think it's ok
that we move forward with replicating the same faulty logic that we have
in the sysfs interface and then fix rproc_shutdown() so that it
internally checks the current state and return appropriately.
Regards,
Bjorn
> > + rproc_shutdown(rproc);
> > +
> > + return 0;
> > +}
> > +
> > +static const struct file_operations rproc_fops = {
> > + .write = rproc_cdev_write,
> > + .compat_ioctl = rproc_device_ioctl,
> > + .release = rproc_cdev_release,
> > +};
> > +
> > +int rproc_char_device_add(struct rproc *rproc)
> > +{
> > + int ret;
> > + dev_t cdevt;
> > +
> > + cdev_init(&rproc->char_dev, &rproc_fops);
> > + rproc->char_dev.owner = THIS_MODULE;
> > +
> > + cdevt = MKDEV(rproc_major, rproc->index);
> > + ret = cdev_add(&rproc->char_dev, cdevt, 1);
> > + if (ret < 0)
> > + goto out;
> > +
> > + rproc->dev.devt = cdevt;
> > +out:
> > + return ret;
> > +}
> > +
> > +void rproc_char_device_remove(struct rproc *rproc)
> > +{
> > + __unregister_chrdev(rproc_major, rproc->index, 1, "remoteproc");
> > +}
> > +
> > +void __init rproc_init_cdev(void)
> > +{
> > + int ret;
> > +
> > + ret = alloc_chrdev_region(&rproc_major, 0, NUM_RPROC_DEVICES, "remoteproc");
> > + if (ret < 0)
> > + pr_err("Failed to alloc rproc_cdev region, err %d\n", ret);
> > +}
> > +
> > +void __exit rproc_exit_cdev(void)
> > +{
> > + unregister_chrdev_region(MKDEV(rproc_major, 0), NUM_RPROC_DEVICES);
>
> Please go back to the comment I made on this during my last review and respin.
>
> > +}
> > diff --git a/drivers/remoteproc/remoteproc_internal.h b/drivers/remoteproc/remoteproc_internal.h
> > index 4ba7cb5..f091ddc 100644
> > --- a/drivers/remoteproc/remoteproc_internal.h
> > +++ b/drivers/remoteproc/remoteproc_internal.h
> > @@ -47,6 +47,34 @@ extern struct class rproc_class;
> > int rproc_init_sysfs(void);
> > void rproc_exit_sysfs(void);
> >
> > +#ifdef CONFIG_REMOTEPROC_CDEV
> > +void rproc_init_cdev(void);
> > +void rproc_exit_cdev(void);
> > +int rproc_char_device_add(struct rproc *rproc);
> > +void rproc_char_device_remove(struct rproc *rproc);
> > +#else
> > +static inline void rproc_init_cdev(void)
> > +{
> > +}
> > +
> > +static inline void rproc_exit_cdev(void)
> > +{
> > +}
> > +
> > +/*
> > + * The character device interface is an optional feature, if it is not enabled
> > + * the function should not return an error.
> > + */
> > +static inline int rproc_char_device_add(struct rproc *rproc)
> > +{
> > + return 0;
> > +}
> > +
> > +static inline void rproc_char_device_remove(struct rproc *rproc)
> > +{
> > +}
> > +#endif
> > +
> > void rproc_free_vring(struct rproc_vring *rvring);
> > int rproc_alloc_vring(struct rproc_vdev *rvdev, int i);
> >
> > diff --git a/include/linux/remoteproc.h b/include/linux/remoteproc.h
> > index e7b7bab..669cbfb 100644
> > --- a/include/linux/remoteproc.h
> > +++ b/include/linux/remoteproc.h
> > @@ -40,6 +40,7 @@
> > #include <linux/virtio.h>
> > #include <linux/completion.h>
> > #include <linux/idr.h>
> > +#include <linux/cdev.h>
>
> Move this above completion.h
>
> With all of the above modifications:
>
> Reviewed-by: Mathieu Poirier <mathieu.poirier at linaro.org>
>
> > #include <linux/of.h>
> >
> > /**
> > @@ -488,6 +489,8 @@ struct rproc_dump_segment {
> > * @auto_boot: flag to indicate if remote processor should be auto-started
> > * @dump_segments: list of segments in the firmware
> > * @nb_vdev: number of vdev currently handled by rproc
> > + * @char_dev: character device of the rproc
> > + * @cdev_put_on_release: flag to indicate if remoteproc should be shutdown on @char_dev release
> > */
> > struct rproc {
> > struct list_head node;
> > @@ -523,6 +526,8 @@ struct rproc {
> > int nb_vdev;
> > u8 elf_class;
> > u16 elf_machine;
> > + struct cdev char_dev;
> > + bool cdev_put_on_release;
> > };
> >
> > /**
> > diff --git a/include/uapi/linux/remoteproc_cdev.h b/include/uapi/linux/remoteproc_cdev.h
> > new file mode 100644
> > index 0000000..c43768e
> > --- /dev/null
> > +++ b/include/uapi/linux/remoteproc_cdev.h
> > @@ -0,0 +1,37 @@
> > +/* SPDX-License-Identifier: GPL-2.0-only WITH Linux-syscall-note */
> > +/*
> > + * IOCTLs for Remoteproc's character device interface.
> > + *
> > + * Copyright (c) 2020, The Linux Foundation. All rights reserved.
> > + */
> > +
> > +#ifndef _UAPI_REMOTEPROC_CDEV_H_
> > +#define _UAPI_REMOTEPROC_CDEV_H_
> > +
> > +#include <linux/ioctl.h>
> > +#include <linux/types.h>
> > +
> > +#define RPROC_MAGIC 0xB7
> > +
> > +/*
> > + * The RPROC_SET_SHUTDOWN_ON_RELEASE ioctl allows to enable/disable the shutdown of a remote
> > + * processor automatically when the controlling userpsace closes the char device interface.
> > + *
> > + * input parameter: integer
> > + * 0 : disable automatic shutdown
> > + * other : enable automatic shutdown
> > + */
> > +#define RPROC_SET_SHUTDOWN_ON_RELEASE _IOW(RPROC_MAGIC, 1, __s32)
> > +
> > +/*
> > + * The RPROC_GET_SHUTDOWN_ON_RELEASE ioctl gets information about whether the automatic shutdown of
> > + * a remote processor is enabled or disabled when the controlling userspace closes the char device
> > + * interface.
> > + *
> > + * output parameter: integer
> > + * 0 : automatic shutdown disable
> > + * other : automatic shutdown enable
> > + */
> > +#define RPROC_GET_SHUTDOWN_ON_RELEASE _IOR(RPROC_MAGIC, 2, __s32)
> > +
> > +#endif
> > --
> > Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
> > a Linux Foundation Collaborative Project
> >
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