Re: [PATCH v6 3/3] remoteproc: Add coredump debugfs entry

Sibi Sankar
2020-07-01T20:22:59Z

On 2020-06-30 01:32, Rishabh Bhatnagar wrote:
> Add coredump debugfs entry to configure the type of dump that will
> be collected during recovery. User can select between default or
> inline coredump functionality. Also coredump collection can be
> disabled through this interface.
> This functionality can be configured differently for different
> remote processors.
>
> Signed-off-by: Rishabh Bhatnagar <rishabhb@codeaurora.org>
> Reviewed-by: Bjorn Andersson <bjorn.andersson@linaro.org>
> Reviewed-by: Mathieu Poirier <mathieu.poirier@linaro.org>
> ---
> drivers/remoteproc/remoteproc_debugfs.c | 86
> +++++++++++++++++++++++++++++++++
> 1 file changed, 86 insertions(+)
>
> diff --git a/drivers/remoteproc/remoteproc_debugfs.c
> b/drivers/remoteproc/remoteproc_debugfs.c
> index 732770e..cca0a91 100644
> --- a/drivers/remoteproc/remoteproc_debugfs.c
> +++ b/drivers/remoteproc/remoteproc_debugfs.c
> @@ -28,6 +28,90 @@
> static struct dentry *rproc_dbg;
>
> /*
> + * A coredump-configuration-to-string lookup table, for exposing a
> + * human readable configuration via debugfs. Always keep in sync with
> + * enum rproc_coredump_mechanism
> + */
> +static const char * const rproc_coredump_str[] = {
> + [RPROC_COREDUMP_DEFAULT] = "default",
> + [RPROC_COREDUMP_INLINE] = "inline",
> + [RPROC_COREDUMP_DISABLED] = "disabled",
> +};
> +
> +/* Expose the current coredump configuration via debugfs */
> +static ssize_t rproc_coredump_read(struct file *filp, char __user
> *userbuf,
> + size_t count, loff_t *ppos)
> +{
> + struct rproc *rproc = filp->private_data;
> + const char *buf = rproc_coredump_str[rproc->dump_conf];

Nit: It would be nice to have a
line feed after the string.

Tested-by: Sibi Sankar <sibis@codeaurora.org>
Reviewed-by: Sibi Sankar <sibis@codeaurora.org>

> +
> + return simple_read_from_buffer(userbuf, count, ppos, buf,
> strlen(buf));
> +}
> +
> +/*
> + * By writing to the 'coredump' debugfs entry, we control the behavior
> of the
> + * coredump mechanism dynamically. The default value of this entry is
> "default".
> + *
> + * The 'coredump' debugfs entry supports these commands:
> + *
> + * default: This is the default coredump mechanism. When the
> remoteproc
> + * crashes the entire coredump will be copied to a separate buffer
> + * and exposed to userspace.
> + *
> + * inline: The coredump will not be copied to a separate buffer and
> the
> + * recovery process will have to wait until data is read by
> + * userspace. But this avoid usage of extra memory.
> + *
> + * disabled: This will disable coredump. Recovery will proceed without
> + * collecting any dump.
> + */
> +static ssize_t rproc_coredump_write(struct file *filp,
> + const char __user *user_buf, size_t count,
> + loff_t *ppos)
> +{
> + struct rproc *rproc = filp->private_data;
> + int ret, err = 0;
> + char buf[20];
> +
> + if (count > sizeof(buf))
> + return -EINVAL;
> +
> + ret = copy_from_user(buf, user_buf, count);
> + if (ret)
> + return -EFAULT;
> +
> + /* remove end of line */
> + if (buf[count - 1] == '\n')
> + buf[count - 1] = '\0';
> +
> + if (rproc->state == RPROC_CRASHED) {
> + dev_err(&rproc->dev, "can't change coredump configuration\n");
> + err = -EBUSY;
> + goto out;
> + }
> +
> + if (!strncmp(buf, "disable", count)) {
> + rproc->dump_conf = RPROC_COREDUMP_DISABLED;
> + } else if (!strncmp(buf, "inline", count)) {
> + rproc->dump_conf = RPROC_COREDUMP_INLINE;
> + } else if (!strncmp(buf, "default", count)) {
> + rproc->dump_conf = RPROC_COREDUMP_DEFAULT;
> + } else {
> + dev_err(&rproc->dev, "Invalid coredump configuration\n");
> + err = -EINVAL;
> + }
> +out:
> + return err ? err : count;
> +}
> +
> +static const struct file_operations rproc_coredump_fops = {
> + .read = rproc_coredump_read,
> + .write = rproc_coredump_write,
> + .open = simple_open,
> + .llseek = generic_file_llseek,
> +};
> +
> +/*
> * Some remote processors may support dumping trace logs into a shared
> * memory buffer. We expose this trace buffer using debugfs, so users
> * can easily tell what's going on remotely.
> @@ -337,6 +421,8 @@ void rproc_create_debug_dir(struct rproc *rproc)
> rproc, &rproc_rsc_table_fops);
> debugfs_create_file("carveout_memories", 0400, rproc->dbg_dir,
> rproc, &rproc_carveouts_fops);
> + debugfs_create_file("coredump", 0600, rproc->dbg_dir,
> + rproc, &rproc_coredump_fops);
> }
>
> void __init rproc_init_debugfs(void)

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