The module auto-unload might seem like a nice optimization, but
it encourages inconsistent behaviour. And behaviour that is
different from all other normal modules.
rbtree_test.c and percpu_test.c returns -EAGAIN from module_init()
on successful completion. Normal module return 0 on success but
returning -EAGAIN perform auto module unloading which seem like
a nice optimization but it brings inconsistent behaviour as well.
I face the similar problem in my previous patch, "Paul Gortmaker"
gives nice review comment on module auto-unloading brings
inconsistent behaviour.
Imagine something as simple as this:
for i in $LIST ; do
modprobe $i
lsmod | grep -q $i
if [ $? != 0 ]; then echo Module $i is not present! ; fi
done
OK, not ideal code, ignoring the modprobe return -- but what it reports
is true --
rbtree_test.c and percpu_test.c test module (if it passed) will NOT be
present.
All other modules from linux/lib/* follow the same semantics that
module_init() returns 0 on successful completion & let external entity
like rmmod do the module unloading task.
Signed-off-by: Pravin Shedge <[email protected]>
---
lib/percpu_test.c | 3 ++-
lib/rbtree_test.c | 2 +-
2 files changed, 3 insertions(+), 2 deletions(-)
diff --git a/lib/percpu_test.c b/lib/percpu_test.c
index 0b5d14d..57a637b 100644
--- a/lib/percpu_test.c
+++ b/lib/percpu_test.c
@@ -123,7 +123,8 @@ static int __init percpu_test_init(void)
preempt_enable();
pr_info("percpu test done\n");
- return -EAGAIN; /* Fail will directly unload the module */
+
+ return 0;
}
static void __exit percpu_test_exit(void)
diff --git a/lib/rbtree_test.c b/lib/rbtree_test.c
index 7d36c1e..5c52112 100644
--- a/lib/rbtree_test.c
+++ b/lib/rbtree_test.c
@@ -394,7 +394,7 @@ static int __init rbtree_test_init(void)
kfree(nodes);
- return -EAGAIN; /* Fail will directly unload the module */
+ return 0;
}
static void __exit rbtree_test_exit(void)
--
2.7.4
On Sat, Dec 23, 2017 at 5:28 PM, Pravin Shedge
<[email protected]> wrote:
> The module auto-unload might seem like a nice optimization, but
> it encourages inconsistent behaviour. And behaviour that is
> different from all other normal modules.
>
> rbtree_test.c and percpu_test.c returns -EAGAIN from module_init()
> on successful completion. Normal module return 0 on success but
> returning -EAGAIN perform auto module unloading which seem like
> a nice optimization but it brings inconsistent behaviour as well.
>
> I face the similar problem in my previous patch, "Paul Gortmaker"
> gives nice review comment on module auto-unloading brings
> inconsistent behaviour.
>
> Imagine something as simple as this:
>
> for i in $LIST ; do
> modprobe $i
> lsmod | grep -q $i
> if [ $? != 0 ]; then echo Module $i is not present! ; fi
> done
>
> OK, not ideal code, ignoring the modprobe return -- but what it reports
> is true --
> rbtree_test.c and percpu_test.c test module (if it passed) will NOT be
> present.
>
> All other modules from linux/lib/* follow the same semantics that
> module_init() returns 0 on successful completion & let external entity
> like rmmod do the module unloading task.
>
Suggested-by: Andrew ... ?
> Signed-off-by: Pravin Shedge <[email protected]>
> ---
> lib/percpu_test.c | 3 ++-
> lib/rbtree_test.c | 2 +-
> 2 files changed, 3 insertions(+), 2 deletions(-)
>
> diff --git a/lib/percpu_test.c b/lib/percpu_test.c
> index 0b5d14d..57a637b 100644
> --- a/lib/percpu_test.c
> +++ b/lib/percpu_test.c
> @@ -123,7 +123,8 @@ static int __init percpu_test_init(void)
> preempt_enable();
>
> pr_info("percpu test done\n");
> - return -EAGAIN; /* Fail will directly unload the module */
> +
> + return 0;
> }
>
> static void __exit percpu_test_exit(void)
> diff --git a/lib/rbtree_test.c b/lib/rbtree_test.c
> index 7d36c1e..5c52112 100644
> --- a/lib/rbtree_test.c
> +++ b/lib/rbtree_test.c
> @@ -394,7 +394,7 @@ static int __init rbtree_test_init(void)
>
> kfree(nodes);
>
> - return -EAGAIN; /* Fail will directly unload the module */
> + return 0;
> }
>
> static void __exit rbtree_test_exit(void)
> --
> 2.7.4
>
--
With Best Regards,
Andy Shevchenko
On Fri, Dec 29, 2017 at 10:17 PM, Andy Shevchenko
<[email protected]> wrote:
> On Sat, Dec 23, 2017 at 5:28 PM, Pravin Shedge
> <[email protected]> wrote:
>> The module auto-unload might seem like a nice optimization, but
>> it encourages inconsistent behaviour. And behaviour that is
>> different from all other normal modules.
>>
>> rbtree_test.c and percpu_test.c returns -EAGAIN from module_init()
>> on successful completion. Normal module return 0 on success but
>> returning -EAGAIN perform auto module unloading which seem like
>> a nice optimization but it brings inconsistent behaviour as well.
>>
>> I face the similar problem in my previous patch, "Paul Gortmaker"
>> gives nice review comment on module auto-unloading brings
>> inconsistent behaviour.
>>
>> Imagine something as simple as this:
>>
>> for i in $LIST ; do
>> modprobe $i
>> lsmod | grep -q $i
>> if [ $? != 0 ]; then echo Module $i is not present! ; fi
>> done
>>
>> OK, not ideal code, ignoring the modprobe return -- but what it reports
>> is true --
>> rbtree_test.c and percpu_test.c test module (if it passed) will NOT be
>> present.
>>
>> All other modules from linux/lib/* follow the same semantics that
>> module_init() returns 0 on successful completion & let external entity
>> like rmmod do the module unloading task.
>>
>
> Suggested-by: Andrew ... ?
Hi Andy,
Please check the reference patch "[PATCH] lib: add module unload
support to sort tests" this patch was added for lib/test_sort.c file.
test_sort.c missing unloading feature so I added auto-unload feature
for the same. But after reviewers comment I am agree on the part that
module auto-unload feature will break the consistency from users point
of view.
The reviewers for this patch are Andrew, Paul Gortmaker.
Thanks & Regards,
PraviN
>
>> Signed-off-by: Pravin Shedge <[email protected]>
>> ---
>> lib/percpu_test.c | 3 ++-
>> lib/rbtree_test.c | 2 +-
>> 2 files changed, 3 insertions(+), 2 deletions(-)
>>
>> diff --git a/lib/percpu_test.c b/lib/percpu_test.c
>> index 0b5d14d..57a637b 100644
>> --- a/lib/percpu_test.c
>> +++ b/lib/percpu_test.c
>> @@ -123,7 +123,8 @@ static int __init percpu_test_init(void)
>> preempt_enable();
>>
>> pr_info("percpu test done\n");
>> - return -EAGAIN; /* Fail will directly unload the module */
>> +
>> + return 0;
>> }
>>
>> static void __exit percpu_test_exit(void)
>> diff --git a/lib/rbtree_test.c b/lib/rbtree_test.c
>> index 7d36c1e..5c52112 100644
>> --- a/lib/rbtree_test.c
>> +++ b/lib/rbtree_test.c
>> @@ -394,7 +394,7 @@ static int __init rbtree_test_init(void)
>>
>> kfree(nodes);
>>
>> - return -EAGAIN; /* Fail will directly unload the module */
>> + return 0;
>> }
>>
>> static void __exit rbtree_test_exit(void)
>> --
>> 2.7.4
>>
>
>
>
> --
> With Best Regards,
> Andy Shevchenko