dm target: use module refcount directly
The tt_internal's 'use' field is superfluous: the module's refcount can do the work properly. An acceptable side-effect is that this increases the reference counts reported by 'lsmod'. Remove the superfluous test when removing a target module. [Crash possible without this on SMP - agk] Cc: stable@kernel.org Signed-off-by: Cheng Renquan <crquan@gmail.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com> Reviewed-by: Alasdair G Kergon <agk@redhat.com> Reviewed-by: Jonathan Brassow <jbrassow@redhat.com>
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@ -18,7 +18,6 @@ struct tt_internal {
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struct target_type tt;
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struct target_type tt;
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struct list_head list;
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struct list_head list;
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long use;
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};
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};
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static LIST_HEAD(_targets);
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static LIST_HEAD(_targets);
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@ -44,12 +43,8 @@ static struct tt_internal *get_target_type(const char *name)
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down_read(&_lock);
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down_read(&_lock);
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ti = __find_target_type(name);
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ti = __find_target_type(name);
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if (ti) {
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if (ti && !try_module_get(ti->tt.module))
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if ((ti->use == 0) && !try_module_get(ti->tt.module))
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ti = NULL;
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ti = NULL;
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else
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ti->use++;
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}
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up_read(&_lock);
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up_read(&_lock);
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return ti;
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return ti;
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@ -77,10 +72,7 @@ void dm_put_target_type(struct target_type *t)
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struct tt_internal *ti = (struct tt_internal *) t;
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struct tt_internal *ti = (struct tt_internal *) t;
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down_read(&_lock);
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down_read(&_lock);
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if (--ti->use == 0)
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module_put(ti->tt.module);
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module_put(ti->tt.module);
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BUG_ON(ti->use < 0);
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up_read(&_lock);
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up_read(&_lock);
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return;
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return;
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@ -140,12 +132,6 @@ void dm_unregister_target(struct target_type *t)
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BUG();
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BUG();
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}
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}
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if (ti->use) {
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DMCRIT("Attempt to unregister target still in use: %s",
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t->name);
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BUG();
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}
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list_del(&ti->list);
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list_del(&ti->list);
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kfree(ti);
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kfree(ti);
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