Re: [PATCH 3/3] crypto: hwrng add sysfs attribute to show user selected rng

[PrasannaKumar Muralidharan]

Hi Harald,

> Hello PrasannaKumar
>
> here is now a version which combines patch 2 and patch 3 together
> according to your suggestions:
>
> == cut ==
>
> From: Harald Freudenberger 
> Date: Fri, 30 Jun 2017 17:06:40 +0200
> Subject: [PATCH 2/2] crypto: hwrng remember rng chosen by user
>
> When a user chooses a rng source via sysfs attribute
> this rng should be sticky, even when other sources
> with better quality to register. This patch introduces
> a simple way to remember the user's choice. This is
> reflected by a new sysfs attribute file 'rng_selected'
> which shows if the current rng has been chosen by
> userspace. The new attribute file shows '1' for user
> selected rng and '0' otherwise.
>
> Signed-off-by: Harald Freudenberger 
> ---
>  drivers/char/hw_random/core.c | 21 +++--
>  1 file changed, 19 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/char/hw_random/core.c b/drivers/char/hw_random/core.c
> index e9dda16..9701ac7 100644
> --- a/drivers/char/hw_random/core.c
> +++ b/drivers/char/hw_random/core.c
> @@ -28,6 +28,8 @@
>  #define RNG_MODULE_NAME"hw_random"
>
>  static struct hwrng *current_rng;
> +/* the current rng has been explicitly chosen by user via sysfs */
> +static int cur_rng_set_by_user;
>  static struct task_struct *hwrng_fill;
>  /* list of registered rngs, sorted decending by quality */
>  static LIST_HEAD(rng_list);
> @@ -304,6 +306,7 @@ static ssize_t hwrng_attr_current_store(struct device 
> *dev,
>  list_for_each_entry(rng, _list, list) {
>  if (sysfs_streq(rng->name, buf)) {
>  err = 0;
> +cur_rng_set_by_user = 1;
>  if (rng != current_rng)
>  err = set_current_rng(rng);
>  break;
> @@ -352,16 +355,27 @@ static ssize_t hwrng_attr_available_show(struct device 
> *dev,
>  return strlen(buf);
>  }
>
> +static ssize_t hwrng_attr_selected_show(struct device *dev,
> +struct device_attribute *attr,
> +char *buf)
> +{
> +return snprintf(buf, PAGE_SIZE, "%d\n", cur_rng_set_by_user);
> +}
> +
>  static DEVICE_ATTR(rng_current, S_IRUGO | S_IWUSR,
> hwrng_attr_current_show,
> hwrng_attr_current_store);
>  static DEVICE_ATTR(rng_available, S_IRUGO,
> hwrng_attr_available_show,
> NULL);
> +static DEVICE_ATTR(rng_selected, S_IRUGO,
> +   hwrng_attr_selected_show,
> +   NULL);
>
>  static struct attribute *rng_dev_attrs[] = {
>  _attr_rng_current.attr,
>  _attr_rng_available.attr,
> +_attr_rng_selected.attr,
>  NULL
>  };
>
> @@ -444,10 +458,12 @@ int hwrng_register(struct hwrng *rng)
>
>  old_rng = current_rng;
>  err = 0;
> -if (!old_rng || (rng->quality > old_rng->quality)) {
> +if (!old_rng ||
> +(!cur_rng_set_by_user && rng->quality > old_rng->quality)) {
>  /*
>   * Set new rng as current as the new rng source
> - * provides better entropy quality.
> + * provides better entropy quality and was not
> + * chosen by userspace.
>   */
>  err = set_current_rng(rng);
>  if (err)
> @@ -479,6 +495,7 @@ void hwrng_unregister(struct hwrng *rng)
>  list_del(>list);
>  if (current_rng == rng) {
>  drop_current_rng();
> +cur_rng_set_by_user = 0;
>  /* rng_list is sorted by quality, use the best (=first) one */
>  if (!list_empty(_list)) {
>  struct hwrng *new_rng;
> --
> 2.7.4
>
> == cut ==
>

Good work, patch looks good to me. Reviewed-by: PrasannaKumar
Muralidharan .
I am wondering if you want to make a v2 of the whole series. You can
just put your patch 1 and 2 and send it again with description.
Requiring a v2 depends on how Herbert prefers to take patches in.

Herbert, Do you prefer a v2 of the patch series or you can take this
version of patch 2?

Note: If you are re-posting this patch as v2 please add my reviewed by
tag for both the patches.

Regards,
PrasannaKumar

Re: [PATCH 3/3] crypto: hwrng add sysfs attribute to show user selected rng

[PrasannaKumar Muralidharan]

Hi Harald,

> Here is an updated version with just showing 0 or 1 in the new sysfs
> attribute file:
> == cut ==
> From: Harald Freudenberger 
> Date: Mon, 3 Jul 2017 10:19:22 +0200
> Subject: [PATCH 3/3] crypto: hwrng add sysfs attribute to show user selected
>  rng
>
> This patch introduces a new sysfs attribute file 'rng_selected'
> which shows if the current rng has been chosen by userspace.
>
> If a rng source is chosen by user via echo some valid string
> to rng_current there should be a way to signal this choice to
> userspace. The new attribute file 'rng_selected' shows '1' for
> user selecte rng and '0' otherwise.
>
> Signed-off-by: Harald Freudenberger 
> ---
>  drivers/char/hw_random/core.c | 21 -
>  1 file changed, 16 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/char/hw_random/core.c b/drivers/char/hw_random/core.c
> index ffd4e36..2b4c7f6 100644
> --- a/drivers/char/hw_random/core.c
> +++ b/drivers/char/hw_random/core.c
> @@ -28,8 +28,8 @@
>  #define RNG_MODULE_NAME"hw_random"
>
>  static struct hwrng *current_rng;
> -/* the current rng has been explicitly chosen by user via sysfs */
> -static int cur_rng_set_by_user;
> +/* the rng explicitly selected by user via sysfs */
> +static struct hwrng *selected_rng;
>  static struct task_struct *hwrng_fill;
>  /* list of registered rngs, sorted decending by quality */
>  static LIST_HEAD(rng_list);
> @@ -306,7 +306,7 @@ static ssize_t hwrng_attr_current_store(struct device 
> *dev,
>  list_for_each_entry(rng, _list, list) {
>  if (sysfs_streq(rng->name, buf)) {
>  err = 0;
> -cur_rng_set_by_user = 1;
> +selected_rng = rng;
>  if (rng != current_rng)
>  err = set_current_rng(rng);
>  break;
> @@ -355,16 +355,27 @@ static ssize_t hwrng_attr_available_show(struct device 
> *dev,
>  return strlen(buf);
>  }
>
> +static ssize_t hwrng_attr_selected_show(struct device *dev,
> +struct device_attribute *attr,
> +char *buf)
> +{
> +return snprintf(buf, PAGE_SIZE, "%d\n", selected_rng ? 1 : 0);
> +}
> +
>  static DEVICE_ATTR(rng_current, S_IRUGO | S_IWUSR,
> hwrng_attr_current_show,
> hwrng_attr_current_store);
>  static DEVICE_ATTR(rng_available, S_IRUGO,
> hwrng_attr_available_show,
> NULL);
> +static DEVICE_ATTR(rng_selected, S_IRUGO,
> +   hwrng_attr_selected_show,
> +   NULL);
>
>  static struct attribute *rng_dev_attrs[] = {
>  _attr_rng_current.attr,
>  _attr_rng_available.attr,
> +_attr_rng_selected.attr,
>  NULL
>  };
>
> @@ -448,7 +459,7 @@ int hwrng_register(struct hwrng *rng)
>  old_rng = current_rng;
>  err = 0;
>  if (!old_rng ||
> -(!cur_rng_set_by_user && rng->quality > old_rng->quality)) {
> +(!selected_rng && rng->quality > old_rng->quality)) {
>  /*
>   * Set new rng as current as the new rng source
>   * provides better entropy quality and was not
> @@ -484,7 +495,7 @@ void hwrng_unregister(struct hwrng *rng)
>  list_del(>list);
>  if (current_rng == rng) {
>  drop_current_rng();
> -cur_rng_set_by_user = 0;
> +selected_rng = NULL;
>  /* rng_list is sorted by quality, use the best (=first) one */
>  if (!list_empty(_list)) {
>  struct hwrng *new_rng;
> --
> 2.7.4
> == cut ==
>

Nice to see quick turn around time. Why not just use the
cur_rng_set_by_user instead of selected_rng? This way patch 3 won't
change things that patch 2 introduced and patch 3 will become much
smaller. Also I feel folding patch 3 and 2 will make sense as both are
related to user selected rng.

Regards,
PrasannaKumar

Re: [PATCH 3/3] crypto: hwrng add sysfs attribute to show user selected rng

[Harald Freudenberger]

On 07/04/2017 03:15 PM, PrasannaKumar Muralidharan wrote:
> On 3 July 2017 at 15:33, Harald Freudenberger  
> wrote:
>> This patch introduces a new sysfs attribute file 'rng_selected'
>> which shows the the rng chosen by userspace.
>>
>> If a rng source is chosen by user via echo some valid string
>> to rng_current there should be a way to signal this choice to
>> userspace. The new attribute file 'rng_selected' shows either
>> the name of the rng chosen or 'none'.
>>
>> Signed-off-by: Harald Freudenberger 
>> ---
>>  drivers/char/hw_random/core.c | 22 +-
>>  1 file changed, 17 insertions(+), 5 deletions(-)
>>
>> diff --git a/drivers/char/hw_random/core.c b/drivers/char/hw_random/core.c
>> index ffd4e36..6a6276a 100644
>> --- a/drivers/char/hw_random/core.c
>> +++ b/drivers/char/hw_random/core.c
>> @@ -28,8 +28,8 @@
>>  #define RNG_MODULE_NAME"hw_random"
>>
>>  static struct hwrng *current_rng;
>> -/* the current rng has been explicitly chosen by user via sysfs */
>> -static int cur_rng_set_by_user;
>> +/* the rng explicitly selected by user via sysfs */
>> +static struct hwrng *selected_rng;
>>  static struct task_struct *hwrng_fill;
>>  /* list of registered rngs, sorted decending by quality */
>>  static LIST_HEAD(rng_list);
>> @@ -306,7 +306,7 @@ static ssize_t hwrng_attr_current_store(struct device 
>> *dev,
>> list_for_each_entry(rng, _list, list) {
>> if (sysfs_streq(rng->name, buf)) {
>> err = 0;
>> -   cur_rng_set_by_user = 1;
>> +   selected_rng = rng;
>> if (rng != current_rng)
>> err = set_current_rng(rng);
>> break;
>> @@ -355,16 +355,28 @@ static ssize_t hwrng_attr_available_show(struct device 
>> *dev,
>> return strlen(buf);
>>  }
>>
>> +static ssize_t hwrng_attr_selected_show(struct device *dev,
>> +   struct device_attribute *attr,
>> +   char *buf)
>> +{
>> +   return snprintf(buf, PAGE_SIZE, "%s\n",
>> +   selected_rng ? selected_rng->name : "none");
>> +}
>> +
>>  static DEVICE_ATTR(rng_current, S_IRUGO | S_IWUSR,
>>hwrng_attr_current_show,
>>hwrng_attr_current_store);
>>  static DEVICE_ATTR(rng_available, S_IRUGO,
>>hwrng_attr_available_show,
>>NULL);
>> +static DEVICE_ATTR(rng_selected, S_IRUGO,
>> +  hwrng_attr_selected_show,
>> +  NULL);
>>
>>  static struct attribute *rng_dev_attrs[] = {
>> _attr_rng_current.attr,
>> _attr_rng_available.attr,
>> +   _attr_rng_selected.attr,
>> NULL
>>  };
>>
>> @@ -448,7 +460,7 @@ int hwrng_register(struct hwrng *rng)
>> old_rng = current_rng;
>> err = 0;
>> if (!old_rng ||
>> -   (!cur_rng_set_by_user && rng->quality > old_rng->quality)) {
>> +   (!selected_rng && rng->quality > old_rng->quality)) {
>> /*
>>  * Set new rng as current as the new rng source
>>  * provides better entropy quality and was not
>> @@ -484,7 +496,7 @@ void hwrng_unregister(struct hwrng *rng)
>> list_del(>list);
>> if (current_rng == rng) {
>> drop_current_rng();
>> -   cur_rng_set_by_user = 0;
>> +   selected_rng = NULL;
>> /* rng_list is sorted by quality, use the best (=first) one 
>> */
>> if (!list_empty(_list)) {
>> struct hwrng *new_rng;
>> --
>> 2.7.4
>>
> The current_rng sysfs attribute shows currently selected rng. So this
> new attribute can contain 1 to indicate user's choice, 0 otherwise.
>
> Regards,
> PrasannaKumar
>
Here is an updated version with just showing 0 or 1 in the new sysfs
attribute file:
== cut ==
From: Harald Freudenberger 
Date: Mon, 3 Jul 2017 10:19:22 +0200
Subject: [PATCH 3/3] crypto: hwrng add sysfs attribute to show user selected
 rng

This patch introduces a new sysfs attribute file 'rng_selected'
which shows if the current rng has been chosen by userspace.

If a rng source is chosen by user via echo some valid string
to rng_current there should be a way to signal this choice to
userspace. The new attribute file 'rng_selected' shows '1' for
user selecte rng and '0' otherwise.

Signed-off-by: Harald Freudenberger 
---
 drivers/char/hw_random/core.c | 21 -
 1 file changed, 16 insertions(+), 5 deletions(-)

diff --git a/drivers/char/hw_random/core.c b/drivers/char/hw_random/core.c
index ffd4e36..2b4c7f6 100644
--- a/drivers/char/hw_random/core.c
+++ b/drivers/char/hw_random/core.c
@@ -28,8 +28,8 @@
 #define RNG_MODULE_NAME"hw_random"
 
 static struct 

Re: [PATCH 3/3] crypto: hwrng add sysfs attribute to show user selected rng

[PrasannaKumar Muralidharan]

On 3 July 2017 at 15:33, Harald Freudenberger  wrote:
> This patch introduces a new sysfs attribute file 'rng_selected'
> which shows the the rng chosen by userspace.
>
> If a rng source is chosen by user via echo some valid string
> to rng_current there should be a way to signal this choice to
> userspace. The new attribute file 'rng_selected' shows either
> the name of the rng chosen or 'none'.
>
> Signed-off-by: Harald Freudenberger 
> ---
>  drivers/char/hw_random/core.c | 22 +-
>  1 file changed, 17 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/char/hw_random/core.c b/drivers/char/hw_random/core.c
> index ffd4e36..6a6276a 100644
> --- a/drivers/char/hw_random/core.c
> +++ b/drivers/char/hw_random/core.c
> @@ -28,8 +28,8 @@
>  #define RNG_MODULE_NAME"hw_random"
>
>  static struct hwrng *current_rng;
> -/* the current rng has been explicitly chosen by user via sysfs */
> -static int cur_rng_set_by_user;
> +/* the rng explicitly selected by user via sysfs */
> +static struct hwrng *selected_rng;
>  static struct task_struct *hwrng_fill;
>  /* list of registered rngs, sorted decending by quality */
>  static LIST_HEAD(rng_list);
> @@ -306,7 +306,7 @@ static ssize_t hwrng_attr_current_store(struct device 
> *dev,
> list_for_each_entry(rng, _list, list) {
> if (sysfs_streq(rng->name, buf)) {
> err = 0;
> -   cur_rng_set_by_user = 1;
> +   selected_rng = rng;
> if (rng != current_rng)
> err = set_current_rng(rng);
> break;
> @@ -355,16 +355,28 @@ static ssize_t hwrng_attr_available_show(struct device 
> *dev,
> return strlen(buf);
>  }
>
> +static ssize_t hwrng_attr_selected_show(struct device *dev,
> +   struct device_attribute *attr,
> +   char *buf)
> +{
> +   return snprintf(buf, PAGE_SIZE, "%s\n",
> +   selected_rng ? selected_rng->name : "none");
> +}
> +
>  static DEVICE_ATTR(rng_current, S_IRUGO | S_IWUSR,
>hwrng_attr_current_show,
>hwrng_attr_current_store);
>  static DEVICE_ATTR(rng_available, S_IRUGO,
>hwrng_attr_available_show,
>NULL);
> +static DEVICE_ATTR(rng_selected, S_IRUGO,
> +  hwrng_attr_selected_show,
> +  NULL);
>
>  static struct attribute *rng_dev_attrs[] = {
> _attr_rng_current.attr,
> _attr_rng_available.attr,
> +   _attr_rng_selected.attr,
> NULL
>  };
>
> @@ -448,7 +460,7 @@ int hwrng_register(struct hwrng *rng)
> old_rng = current_rng;
> err = 0;
> if (!old_rng ||
> -   (!cur_rng_set_by_user && rng->quality > old_rng->quality)) {
> +   (!selected_rng && rng->quality > old_rng->quality)) {
> /*
>  * Set new rng as current as the new rng source
>  * provides better entropy quality and was not
> @@ -484,7 +496,7 @@ void hwrng_unregister(struct hwrng *rng)
> list_del(>list);
> if (current_rng == rng) {
> drop_current_rng();
> -   cur_rng_set_by_user = 0;
> +   selected_rng = NULL;
> /* rng_list is sorted by quality, use the best (=first) one */
> if (!list_empty(_list)) {
> struct hwrng *new_rng;
> --
> 2.7.4
>

The current_rng sysfs attribute shows currently selected rng. So this
new attribute can contain 1 to indicate user's choice, 0 otherwise.

Regards,
PrasannaKumar