padata: remove stop function

padata_stop() has two callers and is unnecessary in both cases.  When
pcrypt calls it before padata_free(), it's being unloaded so there are
no outstanding padata jobs[0].  When __padata_free() calls it, it's
either along the same path or else pcrypt initialization failed, which
of course means there are also no outstanding jobs.

Removing it simplifies padata and saves text.

[0] https://lore.kernel.org/linux-crypto/20191119225017.mjrak2fwa5vccazl@gondor.apana.org.au/Signed-off-by: Daniel Jordan <daniel.m.jordan@oracle.com>
Cc: Herbert Xu <herbert@gondor.apana.org.au>
Cc: Steffen Klassert <steffen.klassert@secunet.com>
Cc: linux-crypto@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

Documentation/core-api/padata.rst

@@ -31,18 +31,7 @@ padata_instance structure for overall control of how jobs are to be run::
 
 'name' simply identifies the instance.
 
-There are functions for enabling and disabling the instance::
-
-    int padata_start(struct padata_instance *pinst);
-    void padata_stop(struct padata_instance *pinst);
-
-These functions are setting or clearing the "PADATA_INIT" flag; if that flag is
-not set, other functions will refuse to work.  padata_start() returns zero on
-success (flag set) or -EINVAL if the padata cpumask contains no active CPU
-(flag not set).  padata_stop() clears the flag and blocks until the padata
-instance is unused.
-
-Finally, complete padata initialization by allocating a padata_shell::
+Then, complete padata initialization by allocating a padata_shell::
 
    struct padata_shell *padata_alloc_shell(struct padata_instance *pinst);
 
@@ -155,11 +144,10 @@ submitted.
 Destroying
 ----------
 
-Cleaning up a padata instance predictably involves calling the three free
+Cleaning up a padata instance predictably involves calling the two free
 functions that correspond to the allocation in reverse::
 
     void padata_free_shell(struct padata_shell *ps);
-    void padata_stop(struct padata_instance *pinst);
     void padata_free(struct padata_instance *pinst);
 
 It is the user's responsibility to ensure all outstanding jobs are complete

crypto/pcrypt.c

@@ -327,12 +327,6 @@ static int pcrypt_init_padata(struct padata_instance **pinst, const char *name)
 	return ret;
 }
 
-static void pcrypt_fini_padata(struct padata_instance *pinst)
-{
-	padata_stop(pinst);
-	padata_free(pinst);
-}
-
 static struct crypto_template pcrypt_tmpl = {
 	.name = "pcrypt",
 	.create = pcrypt_create,
@@ -358,7 +352,7 @@ static int __init pcrypt_init(void)
 	return crypto_register_template(&pcrypt_tmpl);
 
 err_deinit_pencrypt:
-	pcrypt_fini_padata(pencrypt);
+	padata_free(pencrypt);
 err_unreg_kset:
 	kset_unregister(pcrypt_kset);
 err:
@@ -369,8 +363,8 @@ static void __exit pcrypt_exit(void)
 {
 	crypto_unregister_template(&pcrypt_tmpl);
 
-	pcrypt_fini_padata(pencrypt);
-	pcrypt_fini_padata(pdecrypt);
+	padata_free(pencrypt);
+	padata_free(pdecrypt);
 
 	kset_unregister(pcrypt_kset);
 }

include/linux/padata.h

@@ -204,5 +204,4 @@ extern void padata_do_serial(struct padata_priv *padata);
 extern void __init padata_do_multithreaded(struct padata_mt_job *job);
 extern int padata_set_cpumask(struct padata_instance *pinst, int cpumask_type,
 			      cpumask_var_t cpumask);
-extern void padata_stop(struct padata_instance *pinst);
 #endif

kernel/padata.c

@@ -789,19 +789,6 @@ int padata_set_cpumask(struct padata_instance *pinst, int cpumask_type,
 }
 EXPORT_SYMBOL(padata_set_cpumask);
 
-/**
- * padata_stop - stop the parallel processing
- *
- * @pinst: padata instance to stop
- */
-void padata_stop(struct padata_instance *pinst)
-{
-	mutex_lock(&pinst->lock);
-	__padata_stop(pinst);
-	mutex_unlock(&pinst->lock);
-}
-EXPORT_SYMBOL(padata_stop);
-
 #ifdef CONFIG_HOTPLUG_CPU
 
 static int __padata_add_cpu(struct padata_instance *pinst, int cpu)
@@ -883,7 +870,6 @@ static void __padata_free(struct padata_instance *pinst)
 
 	WARN_ON(!list_empty(&pinst->pslist));
 
-	padata_stop(pinst);
 	free_cpumask_var(pinst->rcpumask.cbcpu);
 	free_cpumask_var(pinst->rcpumask.pcpu);
 	free_cpumask_var(pinst->cpumask.pcpu);