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Commit b12fdf7d authored by Zachary Warren's avatar Zachary Warren Committed by Greg Kroah-Hartman
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staging: unisys: rework signal remove/insert to avoid sparse lock warnings 



Avoids the following warnings from sparse:
visorchannel_funcs.c:457:9: warning:
 context imbalance in 'visorchannel_signalremove' - different lock contexts for basic block
visorchannel_funcs.c:512:9: warning:
 context imbalance in 'visorchannel_signalinsert' - different lock contexts for basic

These warnings are false positives. Sparse can't track conditional contexts. The change
puts the lock/unlock into the same context by splitting the insert/remove functions each
into a wrapper function that does locking if necessary and an inner function that does the
insert/remove operation.

Signed-off-by: default avatarZachary Warren <conflatulence@gmail.com>
Acked-by: default avatarBenjamin Romer <benjamin.romer@unisys.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent c1f79c74

drivers/staging/unisys/visorchannel/visorchannel_funcs.c

+54 −49
Original line number Diff line number Diff line
@@ -411,27 +411,21 @@ safe_sig_queue_validate(struct signal_queue_header *psafe_sqh, 
	return 1;

}				/* end safe_sig_queue_validate */



BOOL

visorchannel_signalremove(struct visorchannel *channel, u32 queue, void *msg)

static BOOL

signalremove_inner(struct visorchannel *channel, u32 queue, void *msg)

{

	BOOL rc = FALSE;

	struct signal_queue_header sig_hdr;



	if (channel->needs_lock)

		spin_lock(&channel->remove_lock);



	if (!sig_read_header(channel, queue, &sig_hdr)) {

		rc = FALSE;

		goto cleanup;

	}

	if (sig_hdr.head == sig_hdr.tail) {

		rc = FALSE;	/* no signals to remove */

		goto cleanup;

		return FALSE;

	}

	if (sig_hdr.head == sig_hdr.tail)

		return FALSE;	/* no signals to remove */



	sig_hdr.tail = (sig_hdr.tail + 1) % sig_hdr.max_slots;

	if (!sig_read_data(channel, queue, &sig_hdr, sig_hdr.tail, msg)) {

		ERRDRV("sig_read_data failed: (status=%d)\n", rc);

		goto cleanup;

		ERRDRV("sig_read_data failed\n");

		return FALSE;

	}

	sig_hdr.num_received++;
@@ -440,53 +434,54 @@ visorchannel_signalremove(struct visorchannel *channel, u32 queue, void *msg) 
	 */

	mb(); /* required for channel synch */

	if (!SIG_WRITE_FIELD(channel, queue, &sig_hdr, tail)) {

		ERRDRV("visor_memregion_write of Tail failed: (status=%d)\n",

		       rc);

		goto cleanup;

		ERRDRV("visor_memregion_write of Tail failed\n");

		return FALSE;

	}

	if (!SIG_WRITE_FIELD(channel, queue, &sig_hdr, num_received)) {

		ERRDRV("visor_memregion_write of NumSignalsReceived failed: (status=%d)\n",

		       rc);

		goto cleanup;

		ERRDRV("visor_memregion_write of NumSignalsReceived failed\n");

		return FALSE;

	}

	rc = TRUE;

cleanup:

	if (channel->needs_lock)

	return TRUE;

}



BOOL

visorchannel_signalremove(struct visorchannel *channel, u32 queue, void *msg)

{

	BOOL rc;



	if (channel->needs_lock) {

		spin_lock(&channel->remove_lock);

		rc = signalremove_inner(channel, queue, msg);

		spin_unlock(&channel->remove_lock);

	} else {

		rc = signalremove_inner(channel, queue, msg);

	}



	return rc;

}

EXPORT_SYMBOL_GPL(visorchannel_signalremove);



BOOL

visorchannel_signalinsert(struct visorchannel *channel, u32 queue, void *msg)

static BOOL

signalinsert_inner(struct visorchannel *channel, u32 queue, void *msg)

{

	BOOL rc = FALSE;

	struct signal_queue_header sig_hdr;



	if (channel->needs_lock)

		spin_lock(&channel->insert_lock);



	if (!sig_read_header(channel, queue, &sig_hdr)) {

		rc = FALSE;

		goto cleanup;

		return FALSE;

	}



	sig_hdr.head = ((sig_hdr.head + 1) % sig_hdr.max_slots);

	if (sig_hdr.head == sig_hdr.tail) {

		sig_hdr.num_overflows++;

		if (!SIG_WRITE_FIELD(channel, queue, &sig_hdr, num_overflows)) {

			ERRDRV("visor_memregion_write of NumOverflows failed: (status=%d)\n",

			       rc);

			goto cleanup;

		}

		rc = FALSE;

		goto cleanup;

		if (!SIG_WRITE_FIELD(channel, queue, &sig_hdr, num_overflows))

			ERRDRV("visor_memregion_write of NumOverflows failed\n");



		return FALSE;

	}



	if (!sig_write_data(channel, queue, &sig_hdr, sig_hdr.head, msg)) {

		ERRDRV("sig_write_data failed: (status=%d)\n", rc);

		goto cleanup;

		ERRDRV("sig_write_data failed\n");

		return FALSE;

	}

	sig_hdr.num_sent++;
@@ -495,19 +490,29 @@ visorchannel_signalinsert(struct visorchannel *channel, u32 queue, void *msg) 
	 */

	mb(); /* required for channel synch */

	if (!SIG_WRITE_FIELD(channel, queue, &sig_hdr, head)) {

		ERRDRV("visor_memregion_write of Head failed: (status=%d)\n",

		       rc);

		goto cleanup;

		ERRDRV("visor_memregion_write of Head failed\n");

		return FALSE;

	}

	if (!SIG_WRITE_FIELD(channel, queue, &sig_hdr, num_sent)) {

		ERRDRV("visor_memregion_write of NumSignalsSent failed: (status=%d)\n",

		       rc);

		goto cleanup;

		ERRDRV("visor_memregion_write of NumSignalsSent failed\n");

		return FALSE;

	}

	rc = TRUE;

cleanup:

	if (channel->needs_lock)



	return TRUE;

}



BOOL

visorchannel_signalinsert(struct visorchannel *channel, u32 queue, void *msg)

{

	BOOL rc;



	if (channel->needs_lock) {

		spin_lock(&channel->insert_lock);

		rc = signalinsert_inner(channel, queue, msg);

		spin_unlock(&channel->insert_lock);

	} else {

		rc = signalinsert_inner(channel, queue, msg);

	}



	return rc;

}