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SubjectRe: [PATCH 2/2] lib: Remove module auto-unloading which encourages inconsistent behaviour
On Fri, Dec 29, 2017 at 10:17 PM, Andy Shevchenko
<andy.shevchenko@gmail.com> wrote:
> On Sat, Dec 23, 2017 at 5:28 PM, Pravin Shedge
> <pravin.shedge4linux@gmail.com> 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 <pravin.shedge4linux@gmail.com>
>> ---
>> 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

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