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SubjectRe: [PATCH 2/2] fsi: sbefifo: implement FSI_SBEFIFO_READ_TIMEOUT ioctl
Hi Amitay,

On Wed, 15 Dec 2021, at 11:28, Amitay Isaacs wrote:
> FSI_SBEFIFO_READ_TIMEOUT ioctl sets the read timeout (in seconds) for
> the response to *the next* chip-op sent to sbe. The timeout value is
> reset to default after the chip-op.

For the user? Why reset it automatically? To avoid unexpected surprises
in existing code?

> The timeout affects only the read()
> operation on sbefifo device fd.
>
> Signed-off-by: Amitay Isaacs <amitay@ozlabs.org>
> ---
> drivers/fsi/fsi-sbefifo.c | 42 +++++++++++++++++++++++++++++++++++++++
> include/uapi/linux/fsi.h | 6 ++++++
> 2 files changed, 48 insertions(+)
>
> diff --git a/drivers/fsi/fsi-sbefifo.c b/drivers/fsi/fsi-sbefifo.c
> index 9188161f440c..b2654b143b85 100644
> --- a/drivers/fsi/fsi-sbefifo.c
> +++ b/drivers/fsi/fsi-sbefifo.c
> @@ -32,6 +32,8 @@
> #include <linux/vmalloc.h>
> #include <linux/mm.h>
>
> +#include <uapi/linux/fsi.h>
> +
> /*
> * The SBEFIFO is a pipe-like FSI device for communicating with
> * the self boot engine on POWER processors.
> @@ -134,6 +136,7 @@ struct sbefifo_user {
> void *cmd_page;
> void *pending_cmd;
> size_t pending_len;
> + uint32_t read_timeout_ms;
> };
>
> static DEFINE_MUTEX(sbefifo_ffdc_mutex);
> @@ -796,6 +799,7 @@ static int sbefifo_user_open(struct inode *inode,
> struct file *file)
> return -ENOMEM;
> }
> mutex_init(&user->file_lock);
> + user->read_timeout_ms = SBEFIFO_TIMEOUT_START_RSP;
>
> return 0;
> }
> @@ -838,7 +842,11 @@ static ssize_t sbefifo_user_read(struct file
> *file, char __user *buf,
> rc = mutex_lock_interruptible(&sbefifo->lock);
> if (rc)
> goto bail;
> + sbefifo->timeout_start_rsp_ms = user->read_timeout_ms;
> rc = __sbefifo_submit(sbefifo, user->pending_cmd, cmd_len,
> &resp_iter);
> + /* Reset the read timeout after a single chip-op */
> + sbefifo->timeout_start_rsp_ms = SBEFIFO_TIMEOUT_START_RSP;
> + user->read_timeout_ms = SBEFIFO_TIMEOUT_START_RSP;

I guess I was querying this one

> mutex_unlock(&sbefifo->lock);
> if (rc < 0)
> goto bail;
> @@ -847,6 +855,7 @@ static ssize_t sbefifo_user_read(struct file *file,
> char __user *buf,
> rc = len - iov_iter_count(&resp_iter);
> bail:
> sbefifo_release_command(user);
> + user->read_timeout_ms = 0;
> mutex_unlock(&user->file_lock);
> return rc;
> }
> @@ -928,12 +937,45 @@ static int sbefifo_user_release(struct inode
> *inode, struct file *file)
> return 0;
> }
>
> +static int sbefifo_read_timeout(struct sbefifo_user *user, void __user
> **argp)
> +{
> + uint32_t timeout;
> +
> + if (get_user(timeout, (__u32 __user *)argp))

Hmm

> + return -EFAULT;
> + if (timeout < 10 || timeout > 120)
> + return -EINVAL;
> +
> + user->read_timeout_ms = timeout * 1000; /* user timeout is in sec */
> + return 0;
> +}
> +
> +static long sbefifo_user_ioctl(struct file *file, unsigned int cmd,
> unsigned long arg)
> +{
> + struct sbefifo_user *user = file->private_data;
> + void __user **argp = (void __user *)arg;

Why are we doing strange things with the pointer types?

Andrew

> + int rc = -ENOTTY;
> +
> + if (!user)
> + return -EINVAL;
> +
> + mutex_lock(&user->file_lock);
> + switch (cmd) {
> + case FSI_SBEFIFO_READ_TIMEOUT:
> + rc = sbefifo_read_timeout(user, argp);
> + break;
> + }
> + mutex_unlock(&user->file_lock);
> + return rc;
> +}
> +
> static const struct file_operations sbefifo_fops = {
> .owner = THIS_MODULE,
> .open = sbefifo_user_open,
> .read = sbefifo_user_read,
> .write = sbefifo_user_write,
> .release = sbefifo_user_release,
> + .unlocked_ioctl = sbefifo_user_ioctl,
> };
>
> static void sbefifo_free(struct device *dev)
> diff --git a/include/uapi/linux/fsi.h b/include/uapi/linux/fsi.h
> index da577ecd90e7..3e00874ace22 100644
> --- a/include/uapi/linux/fsi.h
> +++ b/include/uapi/linux/fsi.h
> @@ -55,4 +55,10 @@ struct scom_access {
> #define FSI_SCOM_WRITE _IOWR('s', 0x02, struct scom_access)
> #define FSI_SCOM_RESET _IOW('s', 0x03, __u32)
>
> +/*
> + * /dev/sbefifo* ioctl interface
> + */
> +
> +#define FSI_SBEFIFO_READ_TIMEOUT _IOW('s', 0x00, __u32)
> +
> #endif /* _UAPI_LINUX_FSI_H */
> --
> 2.33.1

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