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[PATCH 2/6] hwrng: core: Simplify RNG switching from sysfs

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  [PATCH 2/6] hwrng: core: Simplify RNG switching from sysfs Lee Jones <lee.jones@linaro.org> - 2015-09-11 22:20 +0200
    Re: [PATCH 2/6] hwrng: core: Simplify RNG switching from sysfs Peter Korsgaard <peter@korsgaard.com> - 2015-09-13 16:30 +0200
      Re: [PATCH 2/6] hwrng: core: Simplify RNG switching from sysfs Lee Jones <lee.jones@linaro.org> - 2015-09-14 09:30 +0200

#1223082 — [PATCH 2/6] hwrng: core: Simplify RNG switching from sysfs

If we attempt to use sysfs to change the current RNG in the usual
way i.e. issuing something like:

`echo 8a8a000.rng > /sys/devices/virtual/misc/hw_random/rng_current`

... it will fail because the code doesn't currently take the '\n'
into consideration.  Well, now it does.

Signed-off-by: Lee Jones <lee.jones@linaro.org>
---
 drivers/char/hw_random/core.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/drivers/char/hw_random/core.c b/drivers/char/hw_random/core.c
index da8faf7..14dc984 100644
--- a/drivers/char/hw_random/core.c
+++ b/drivers/char/hw_random/core.c
@@ -316,6 +316,7 @@ static ssize_t hwrng_attr_current_store(struct device *dev,
 					const char *buf, size_t len)
 {
 	int err;
+	int snip = 0;
 	struct hwrng *rng;
 
 	err = mutex_lock_interruptible(&rng_mutex);
@@ -323,7 +324,11 @@ static ssize_t hwrng_attr_current_store(struct device *dev,
 		return -ERESTARTSYS;
 	err = -ENODEV;
 	list_for_each_entry(rng, &rng_list, list) {
-		if (strcmp(rng->name, buf) == 0) {
+
+		if (buf[len-1] == '\n')
+			snip = 1; /* Snip one character */
+
+		if (strncmp(rng->name, buf, len - snip) == 0) {
 			err = 0;
 			if (rng != current_rng)
 				err = set_current_rng(rng);
-- 
1.9.1

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#1223679

>>>>> "Lee" == Lee Jones <lee.jones@linaro.org> writes:

 > If we attempt to use sysfs to change the current RNG in the usual
 > way i.e. issuing something like:

 > `echo 8a8a000.rng > /sys/devices/virtual/misc/hw_random/rng_current`

 > ... it will fail because the code doesn't currently take the '\n'
 > into consideration.  Well, now it does.

 > Signed-off-by: Lee Jones <lee.jones@linaro.org>
 > ---
 >  drivers/char/hw_random/core.c | 7 ++++++-
 >  1 file changed, 6 insertions(+), 1 deletion(-)

 > diff --git a/drivers/char/hw_random/core.c b/drivers/char/hw_random/core.c
 > index da8faf7..14dc984 100644
 > --- a/drivers/char/hw_random/core.c
 > +++ b/drivers/char/hw_random/core.c
 > @@ -316,6 +316,7 @@ static ssize_t hwrng_attr_current_store(struct device *dev,
 >  					const char *buf, size_t len)
 >  {
 >  	int err;
 > +	int snip = 0;
 >  	struct hwrng *rng;
 
 >  	err = mutex_lock_interruptible(&rng_mutex);
 > @@ -323,7 +324,11 @@ static ssize_t hwrng_attr_current_store(struct device *dev,
 >  		return -ERESTARTSYS;
 >  	err = -ENODEV;
 >  	list_for_each_entry(rng, &rng_list, list) {
 > -		if (strcmp(rng->name, buf) == 0) {
 > +
 > +		if (buf[len-1] == '\n')
 > +			snip = 1; /* Snip one character */
 > +

How about using sysfs_streq() instead, which is what is done elsewhere?

-- 
Bye, Peter Korsgaard
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#1223873

On Sun, 13 Sep 2015, Peter Korsgaard wrote:

> >>>>> "Lee" == Lee Jones <lee.jones@linaro.org> writes:
> 
>  > If we attempt to use sysfs to change the current RNG in the usual
>  > way i.e. issuing something like:
> 
>  > `echo 8a8a000.rng > /sys/devices/virtual/misc/hw_random/rng_current`
> 
>  > ... it will fail because the code doesn't currently take the '\n'
>  > into consideration.  Well, now it does.
> 
>  > Signed-off-by: Lee Jones <lee.jones@linaro.org>
>  > ---
>  >  drivers/char/hw_random/core.c | 7 ++++++-
>  >  1 file changed, 6 insertions(+), 1 deletion(-)
> 
>  > diff --git a/drivers/char/hw_random/core.c b/drivers/char/hw_random/core.c
>  > index da8faf7..14dc984 100644
>  > --- a/drivers/char/hw_random/core.c
>  > +++ b/drivers/char/hw_random/core.c
>  > @@ -316,6 +316,7 @@ static ssize_t hwrng_attr_current_store(struct device *dev,
>  >  					const char *buf, size_t len)
>  >  {
>  >  	int err;
>  > +	int snip = 0;
>  >  	struct hwrng *rng;
>  
>  >  	err = mutex_lock_interruptible(&rng_mutex);
>  > @@ -323,7 +324,11 @@ static ssize_t hwrng_attr_current_store(struct device *dev,
>  >  		return -ERESTARTSYS;
>  >  	err = -ENODEV;
>  >  	list_for_each_entry(rng, &rng_list, list) {
>  > -		if (strcmp(rng->name, buf) == 0) {
>  > +
>  > +		if (buf[len-1] == '\n')
>  > +			snip = 1; /* Snip one character */
>  > +
> 
> How about using sysfs_streq() instead, which is what is done elsewhere?

Perfect.  This is exactly what I'm trying to do, thanks.

-- 
Lee Jones
Linaro STMicroelectronics Landing Team Lead
Linaro.org │ Open source software for ARM SoCs
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