linux-kernel - [PATCH V2] staging: gpib: Fix lpvo request_system

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Message-ID: <20250426150319.5580-1-dpenkler@gmail.com>
Date: Sat, 26 Apr 2025 17:03:19 +0200
From: Dave Penkler <dpenkler@...il.com>
To: gregkh@...uxfoundation.org,
	linux-staging@...ts.linux.dev,
	linux-kernel@...r.kernel.org
Cc: marcello.carla@....com,
	dan.carpenter@...aro.org,
	Dave Penkler <dpenkler@...il.com>
Subject: [PATCH V2] staging: gpib: Fix lpvo request_system_control

The IEEE-488 GPIB standard was designed to ensure that there is only ever
one controller-in-charge on the bus at any one time. If a board becomes
controller-in-charge on request_system_control there is no way to ensure
that there is not another board also acting as controller-in-charge.
This can lead to bus conflicts and hangs.

Remove the setting of controller-in-charge from request_system_control.

Fixes: fce79512a96a ("staging: gpib: Add LPVO DIY USB GPIB driver")
Signed-off-by: Dave Penkler <dpenkler@...il.com>
---

Changes V1->V2: Expand commit message to include user impact of bug

 drivers/staging/gpib/lpvo_usb_gpib/lpvo_usb_gpib.c | 1 -
 1 file changed, 1 deletion(-)

diff --git a/drivers/staging/gpib/lpvo_usb_gpib/lpvo_usb_gpib.c b/drivers/staging/gpib/lpvo_usb_gpib/lpvo_usb_gpib.c
index 2e315c7756c4..3cf5037c0cd2 100644
--- a/drivers/staging/gpib/lpvo_usb_gpib/lpvo_usb_gpib.c
+++ b/drivers/staging/gpib/lpvo_usb_gpib/lpvo_usb_gpib.c
@@ -916,7 +916,6 @@ static int usb_gpib_request_system_control(struct gpib_board *board, int request
 	if (!request_control)
 		return -EINVAL;
 
-	set_bit(CIC_NUM, &board->status);
 	DIA_LOG(1, "done with %d -> %lx\n", request_control, board->status);
 	return 0;
 }
-- 
2.49.0