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[PATCH 1/2] powerpc/fadump: return 0 on re-registration

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  [PATCH 1/2] powerpc/fadump: return 0 on re-registration Michal Suchanek <msuchanek@suse.de> - 2017-06-26 16:10 +0200
    [PATCH 2/2] powerpc/fadump: use kstrtoint to handle sysfs store Michal Suchanek <msuchanek@suse.de> - 2017-06-26 16:10 +0200
    Re: [PATCH 1/2] powerpc/fadump: return 0 on re-registration Michal Suchánek <msuchanek@suse.de> - 2017-06-27 11:40 +0200

#1674813 — [PATCH 1/2] powerpc/fadump: return 0 on re-registration

When fadump is already registered return success.

Currently EEXIST is returned which is difficult to handle race-free in
userspace when shell scripts are used. If multiple writers are trying to
write '1' there is no difference in whichever succeeds so just return 0
to all.

Signed-off-by: Michal Suchanek <msuchanek@suse.de>
---
 arch/powerpc/kernel/fadump.c | 1 -
 1 file changed, 1 deletion(-)

diff --git a/arch/powerpc/kernel/fadump.c b/arch/powerpc/kernel/fadump.c
index 436aedf195ab..5a7355381dac 100644
--- a/arch/powerpc/kernel/fadump.c
+++ b/arch/powerpc/kernel/fadump.c
@@ -1214,7 +1214,6 @@ static ssize_t fadump_register_store(struct kobject *kobj,
 		break;
 	case '1':
 		if (fw_dump.dump_registered == 1) {
-			ret = -EEXIST;
 			goto unlock_out;
 		}
 		/* Register Firmware-assisted dump */
-- 
2.10.2

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#1674815 — [PATCH 2/2] powerpc/fadump: use kstrtoint to handle sysfs store

Currently sysfs store handlers in fadump use if buf[0] == 'char'.

This means input "100foo" is interpreted as '1' and "01" as '0'.

Change to kstrtoint so leading zeroes and the like is handled in
expected way.

Signed-off-by: Michal Suchanek <msuchanek@suse.de>
---
 arch/powerpc/kernel/fadump.c | 17 +++++++++++++----
 1 file changed, 13 insertions(+), 4 deletions(-)

diff --git a/arch/powerpc/kernel/fadump.c b/arch/powerpc/kernel/fadump.c
index 5a7355381dac..241eff0b5f76 100644
--- a/arch/powerpc/kernel/fadump.c
+++ b/arch/powerpc/kernel/fadump.c
@@ -1161,10 +1161,15 @@ static ssize_t fadump_release_memory_store(struct kobject *kobj,
 					struct kobj_attribute *attr,
 					const char *buf, size_t count)
 {
+	int input = -1;
+
 	if (!fw_dump.dump_active)
 		return -EPERM;
 
-	if (buf[0] == '1') {
+	if (kstrtoint(buf, 0, &input))
+		return -EINVAL;
+
+	if (input == 1) {
 		/*
 		 * Take away the '/proc/vmcore'. We are releasing the dump
 		 * memory, hence it will not be valid anymore.
@@ -1198,21 +1203,25 @@ static ssize_t fadump_register_store(struct kobject *kobj,
 					const char *buf, size_t count)
 {
 	int ret = 0;
+	int input = -1;
 
 	if (!fw_dump.fadump_enabled || fdm_active)
 		return -EPERM;
 
+	if (kstrtoint(buf, 0, &input))
+		return -EINVAL;
+
 	mutex_lock(&fadump_mutex);
 
-	switch (buf[0]) {
-	case '0':
+	switch (input) {
+	case 0:
 		if (fw_dump.dump_registered == 0) {
 			goto unlock_out;
 		}
 		/* Un-register Firmware-assisted dump */
 		fadump_unregister_dump(&fdm);
 		break;
-	case '1':
+	case 1:
 		if (fw_dump.dump_registered == 1) {
 			goto unlock_out;
 		}
-- 
2.10.2

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#1675460

On Mon, 26 Jun 2017 16:06:00 +0200
Michal Suchanek <msuchanek@suse.de> wrote:

> When fadump is already registered return success.
> 
> Currently EEXIST is returned which is difficult to handle race-free in
> userspace when shell scripts are used. If multiple writers are trying
> to write '1' there is no difference in whichever succeeds so just
> return 0 to all.
> 
> Signed-off-by: Michal Suchanek <msuchanek@suse.de>
> ---
>  arch/powerpc/kernel/fadump.c | 1 -
>  1 file changed, 1 deletion(-)
> 
> diff --git a/arch/powerpc/kernel/fadump.c
> b/arch/powerpc/kernel/fadump.c index 436aedf195ab..5a7355381dac 100644
> --- a/arch/powerpc/kernel/fadump.c
> +++ b/arch/powerpc/kernel/fadump.c
> @@ -1214,7 +1214,6 @@ static ssize_t fadump_register_store(struct
> kobject *kobj, break;
>  	case '1':
>  		if (fw_dump.dump_registered == 1) {
> -			ret = -EEXIST;
>  			goto unlock_out;
>  		}
>  		/* Register Firmware-assisted dump */

Forget about this one.

It breaks another case when fadump is registered and you need to
re-register to account for change in system configuration.

Thanks

Michal

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