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afs: Fix a Sparse warning in xdr_decode_AFSFetchStatus()
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Sparse doesn't appear able to handle the conditionally-taken locks in
xdr_decode_AFSFetchStatus(), even though the lock and unlock are both
contingent on the same unvarying function argument.

Deal with this by interpolating a wrapper function that takes the lock if
needed and calls xdr_decode_AFSFetchStatus() on two separate branches, one
with the lock held and one without.

This allows Sparse to work out the locking.

Signed-off-by: David Howells <dhowells@redhat.com>
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David Howells committed May 23, 2018
1 parent 564def7 commit c875c76
Showing 1 changed file with 55 additions and 42 deletions.
97 changes: 55 additions & 42 deletions fs/afs/fsclient.c
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Original file line number Diff line number Diff line change
Expand Up @@ -137,10 +137,6 @@ static int xdr_decode_AFSFetchStatus(struct afs_call *call,
u64 data_version, size;
u32 type, abort_code;
u8 flags = 0;
int ret;

if (vnode)
write_seqlock(&vnode->cb_lock);

if (xdr->if_version != htonl(AFS_FSTATUS_VERSION)) {
pr_warn("Unknown AFSFetchStatus version %u\n", ntohl(xdr->if_version));
Expand Down Expand Up @@ -168,8 +164,7 @@ static int xdr_decode_AFSFetchStatus(struct afs_call *call,
case AFS_FTYPE_INVALID:
if (abort_code != 0) {
status->abort_code = abort_code;
ret = 0;
goto out;
return 0;
}
/* Fall through */
default:
Expand Down Expand Up @@ -222,17 +217,35 @@ static int xdr_decode_AFSFetchStatus(struct afs_call *call,
flags);
}

ret = 0;

out:
if (vnode)
write_sequnlock(&vnode->cb_lock);
return ret;
return 0;

bad:
xdr_dump_bad(*_bp);
ret = afs_protocol_error(call, -EBADMSG);
goto out;
return afs_protocol_error(call, -EBADMSG);
}

/*
* Decode the file status. We need to lock the target vnode if we're going to
* update its status so that stat() sees the attributes update atomically.
*/
static int afs_decode_status(struct afs_call *call,
const __be32 **_bp,
struct afs_file_status *status,
struct afs_vnode *vnode,
const afs_dataversion_t *expected_version,
struct afs_read *read_req)
{
int ret;

if (!vnode)
return xdr_decode_AFSFetchStatus(call, _bp, status, vnode,
expected_version, read_req);

write_seqlock(&vnode->cb_lock);
ret = xdr_decode_AFSFetchStatus(call, _bp, status, vnode,
expected_version, read_req);
write_sequnlock(&vnode->cb_lock);
return ret;
}

/*
Expand Down Expand Up @@ -374,8 +387,8 @@ static int afs_deliver_fs_fetch_status_vnode(struct afs_call *call)

/* unmarshall the reply once we've received all of it */
bp = call->buffer;
if (xdr_decode_AFSFetchStatus(call, &bp, &vnode->status, vnode,
&call->expected_version, NULL) < 0)
if (afs_decode_status(call, &bp, &vnode->status, vnode,
&call->expected_version, NULL) < 0)
return afs_protocol_error(call, -EBADMSG);
xdr_decode_AFSCallBack(call, vnode, &bp);
if (call->reply[1])
Expand Down Expand Up @@ -555,8 +568,8 @@ static int afs_deliver_fs_fetch_data(struct afs_call *call)
return ret;

bp = call->buffer;
if (xdr_decode_AFSFetchStatus(call, &bp, &vnode->status, vnode,
&vnode->status.data_version, req) < 0)
if (afs_decode_status(call, &bp, &vnode->status, vnode,
&vnode->status.data_version, req) < 0)
return afs_protocol_error(call, -EBADMSG);
xdr_decode_AFSCallBack(call, vnode, &bp);
if (call->reply[1])
Expand Down Expand Up @@ -708,9 +721,9 @@ static int afs_deliver_fs_create_vnode(struct afs_call *call)
/* unmarshall the reply once we've received all of it */
bp = call->buffer;
xdr_decode_AFSFid(&bp, call->reply[1]);
if (xdr_decode_AFSFetchStatus(call, &bp, call->reply[2], NULL, NULL, NULL) < 0 ||
xdr_decode_AFSFetchStatus(call, &bp, &vnode->status, vnode,
&call->expected_version, NULL) < 0)
if (afs_decode_status(call, &bp, call->reply[2], NULL, NULL, NULL) < 0 ||
afs_decode_status(call, &bp, &vnode->status, vnode,
&call->expected_version, NULL) < 0)
return afs_protocol_error(call, -EBADMSG);
xdr_decode_AFSCallBack_raw(&bp, call->reply[3]);
/* xdr_decode_AFSVolSync(&bp, call->reply[X]); */
Expand Down Expand Up @@ -814,8 +827,8 @@ static int afs_deliver_fs_remove(struct afs_call *call)

/* unmarshall the reply once we've received all of it */
bp = call->buffer;
if (xdr_decode_AFSFetchStatus(call, &bp, &vnode->status, vnode,
&call->expected_version, NULL) < 0)
if (afs_decode_status(call, &bp, &vnode->status, vnode,
&call->expected_version, NULL) < 0)
return afs_protocol_error(call, -EBADMSG);
/* xdr_decode_AFSVolSync(&bp, call->reply[X]); */

Expand Down Expand Up @@ -904,9 +917,9 @@ static int afs_deliver_fs_link(struct afs_call *call)

/* unmarshall the reply once we've received all of it */
bp = call->buffer;
if (xdr_decode_AFSFetchStatus(call, &bp, &vnode->status, vnode, NULL, NULL) < 0 ||
xdr_decode_AFSFetchStatus(call, &bp, &dvnode->status, dvnode,
&call->expected_version, NULL) < 0)
if (afs_decode_status(call, &bp, &vnode->status, vnode, NULL, NULL) < 0 ||
afs_decode_status(call, &bp, &dvnode->status, dvnode,
&call->expected_version, NULL) < 0)
return afs_protocol_error(call, -EBADMSG);
/* xdr_decode_AFSVolSync(&bp, call->reply[X]); */

Expand Down Expand Up @@ -991,9 +1004,9 @@ static int afs_deliver_fs_symlink(struct afs_call *call)
/* unmarshall the reply once we've received all of it */
bp = call->buffer;
xdr_decode_AFSFid(&bp, call->reply[1]);
if (xdr_decode_AFSFetchStatus(call, &bp, call->reply[2], NULL, NULL, NULL) ||
xdr_decode_AFSFetchStatus(call, &bp, &vnode->status, vnode,
&call->expected_version, NULL) < 0)
if (afs_decode_status(call, &bp, call->reply[2], NULL, NULL, NULL) ||
afs_decode_status(call, &bp, &vnode->status, vnode,
&call->expected_version, NULL) < 0)
return afs_protocol_error(call, -EBADMSG);
/* xdr_decode_AFSVolSync(&bp, call->reply[X]); */

Expand Down Expand Up @@ -1097,12 +1110,12 @@ static int afs_deliver_fs_rename(struct afs_call *call)

/* unmarshall the reply once we've received all of it */
bp = call->buffer;
if (xdr_decode_AFSFetchStatus(call, &bp, &orig_dvnode->status, orig_dvnode,
&call->expected_version, NULL) < 0)
if (afs_decode_status(call, &bp, &orig_dvnode->status, orig_dvnode,
&call->expected_version, NULL) < 0)
return afs_protocol_error(call, -EBADMSG);
if (new_dvnode != orig_dvnode &&
xdr_decode_AFSFetchStatus(call, &bp, &new_dvnode->status, new_dvnode,
&call->expected_version_2, NULL) < 0)
afs_decode_status(call, &bp, &new_dvnode->status, new_dvnode,
&call->expected_version_2, NULL) < 0)
return afs_protocol_error(call, -EBADMSG);
/* xdr_decode_AFSVolSync(&bp, call->reply[X]); */

Expand Down Expand Up @@ -1206,8 +1219,8 @@ static int afs_deliver_fs_store_data(struct afs_call *call)

/* unmarshall the reply once we've received all of it */
bp = call->buffer;
if (xdr_decode_AFSFetchStatus(call, &bp, &vnode->status, vnode,
&call->expected_version, NULL) < 0)
if (afs_decode_status(call, &bp, &vnode->status, vnode,
&call->expected_version, NULL) < 0)
return afs_protocol_error(call, -EBADMSG);
/* xdr_decode_AFSVolSync(&bp, call->reply[X]); */

Expand Down Expand Up @@ -1382,8 +1395,8 @@ static int afs_deliver_fs_store_status(struct afs_call *call)

/* unmarshall the reply once we've received all of it */
bp = call->buffer;
if (xdr_decode_AFSFetchStatus(call, &bp, &vnode->status, vnode,
&call->expected_version, NULL) < 0)
if (afs_decode_status(call, &bp, &vnode->status, vnode,
&call->expected_version, NULL) < 0)
return afs_protocol_error(call, -EBADMSG);
/* xdr_decode_AFSVolSync(&bp, call->reply[X]); */

Expand Down Expand Up @@ -2084,8 +2097,8 @@ static int afs_deliver_fs_fetch_status(struct afs_call *call)

/* unmarshall the reply once we've received all of it */
bp = call->buffer;
xdr_decode_AFSFetchStatus(call, &bp, status, vnode,
&call->expected_version, NULL);
afs_decode_status(call, &bp, status, vnode,
&call->expected_version, NULL);
callback[call->count].version = ntohl(bp[0]);
callback[call->count].expiry = ntohl(bp[1]);
callback[call->count].type = ntohl(bp[2]);
Expand Down Expand Up @@ -2196,9 +2209,9 @@ static int afs_deliver_fs_inline_bulk_status(struct afs_call *call)

bp = call->buffer;
statuses = call->reply[1];
if (xdr_decode_AFSFetchStatus(call, &bp, &statuses[call->count],
call->count == 0 ? vnode : NULL,
NULL, NULL) < 0)
if (afs_decode_status(call, &bp, &statuses[call->count],
call->count == 0 ? vnode : NULL,
NULL, NULL) < 0)
return afs_protocol_error(call, -EBADMSG);

call->count++;
Expand Down

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