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SubjectRe: dm: change dm_get_target_type() to check for module load error
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On 10/6/21 2:35 PM, Mike Snitzer wrote:
> On Mon, Oct 04 2021 at 4:06P -0400,
> Shuah Khan <skhan@linuxfoundation.org> wrote:
>
>> dm_get_target_type() doesn't check error return from request_module().
>> Change to check for error and return NULL instead of trying to get
>> target type again which would fail.
>>
>> Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>
>> ---
>> drivers/md/dm-target.c | 11 ++++++++---
>> 1 file changed, 8 insertions(+), 3 deletions(-)
>>
>> diff --git a/drivers/md/dm-target.c b/drivers/md/dm-target.c
>> index 64dd0b34fcf4..0789e9f91d3a 100644
>> --- a/drivers/md/dm-target.c
>> +++ b/drivers/md/dm-target.c
>> @@ -41,17 +41,22 @@ static struct target_type *get_target_type(const char *name)
>> return tt;
>> }
>>
>> -static void load_module(const char *name)
>> +static int load_module(const char *name)
>> {
>> - request_module("dm-%s", name);
>> + return request_module("dm-%s", name);
>> }
>>
>> struct target_type *dm_get_target_type(const char *name)
>> {
>> struct target_type *tt = get_target_type(name);
>> + int ret;
>>
>> if (!tt) {
>> - load_module(name);
>> + ret = load_module(name);
>> + if (ret < 0) {
>> + pr_err("Module %s load failed %d\n", name, ret);
>> + return NULL;
>> + }
>> tt = get_target_type(name);
>> }
>>
>> --
>> 2.30.2
>>
>
> While I appreciate your intent, the reality is that multiple targets
> may be made available in a given module. And so loading one dm module
> may bring in access to N targets. There isn't a rigid 1:1 mapping of
> target modules to names. And there may not even be a loadable module
> that has the name dm-${name} -- but that doesn't mean the target_type
> won;t have been loaded into DM for it to access.
>

Thanks for the explanation.

-- Shuah

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