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cred: allow get_cred() and put_cred() to be given NULL.

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It is common practice for helpers like this to silently,
accept a NULL pointer.
get_rpccred() and put_rpccred() used by NFS act this way
and using the same interface will ease the conversion
for NFS, and simplify the resulting code.

Signed-off-by: NeilBrown <neilb@suse.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
This commit is contained in:
NeilBrown 2018-12-03 11:30:30 +11:00 committed by Anna Schumaker
parent a6d8e7637f
commit f06bc03339
1 changed files with 9 additions and 5 deletions
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14
include/linux/cred.h
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@ -237,7 +237,7 @@ static inline struct cred *get_new_cred(struct cred *cred)
* @cred: The credentials to reference
*
* Get a reference on the specified set of credentials. The caller must
* release the reference.
* release the reference. If %NULL is passed, it is returned with no action.
*
* This is used to deal with a committed set of credentials. Although the
* pointer is const, this will temporarily discard the const and increment the
@ -248,6 +248,8 @@ static inline struct cred *get_new_cred(struct cred *cred)
static inline const struct cred *get_cred(const struct cred *cred)
{
struct cred *nonconst_cred = (struct cred *) cred;
if (!cred)
return cred;
validate_creds(cred);
return get_new_cred(nonconst_cred);
}
@ -268,7 +270,7 @@ static inline const struct cred *get_cred_rcu(const struct cred *cred)
* @cred: The credentials to release
*
* Release a reference to a set of credentials, deleting them when the last ref
* is released.
* is released. If %NULL is passed, nothing is done.
*
* This takes a const pointer to a set of credentials because the credentials
* on task_struct are attached by const pointers to prevent accidental
@ -278,9 +280,11 @@ static inline void put_cred(const struct cred *_cred)
{
struct cred *cred = (struct cred *) _cred;
validate_creds(cred);
if (atomic_dec_and_test(&(cred)->usage))
__put_cred(cred);
if (cred) {
validate_creds(cred);
if (atomic_dec_and_test(&(cred)->usage))
__put_cred(cred);
}
}
/**