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From: Yang Shao <shaoyang@uniontech.com>
To: sudipm.mukherjee@gmail.com
Cc: marko.kohtala@gmail.com, akpm@osdl.org,
	linux-kernel@vger.kernel.org, kernel@uniontech.com,
	Yang Shao <shaoyang@uniontech.com>,
	stable@vger.kernel.org
Subject: [PATCH] parport: fix inverted daisy selection result check
Date: Wed, 24 Jun 2026 09:36:03 +0800	[thread overview]
Message-ID: <20260624013603.1184198-1-shaoyang@uniontech.com> (raw)

parport_daisy_select() returns a boolean success result. It returns 1
when the requested daisy-chain device acknowledges the CPP selection
command and 0 otherwise.

Commit 7c9cc3be1094 ("[PATCH] parport: parport_daisy_select return
value fix") changed the helper from returning the raw
PARPORT_STATUS_ERROR bit to returning its logical negation. Selection
success therefore changed from a zero return value to a nonzero return
value, but parport_claim() retained the old zero-is-success test.

As a result, a successful selection does not update port->daisy, while
an unsuccessful selection can be recorded as the currently selected
daisy address. parport_open() later checks port->daisy to determine
whether the requested device was successfully selected, so this can
reject an existing device or accept a device address that was not
selected.

Test the return value directly and update port->daisy only after a
successful selection.

Fixes: 7c9cc3be1094 ("[PATCH] parport: parport_daisy_select return value fix")
Cc: stable@vger.kernel.org
Signed-off-by: Yang Shao <shaoyang@uniontech.com>
---
 drivers/parport/share.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/parport/share.c b/drivers/parport/share.c
index c4c5869..2888005 100644
--- a/drivers/parport/share.c
+++ b/drivers/parport/share.c
@@ -1025,8 +1025,8 @@ int parport_claim(struct pardevice *dev)
 	/* If it's a daisy chain device, select it. */
 	if (dev->daisy >= 0) {
 		/* This could be lazier. */
-		if (!parport_daisy_select(port, dev->daisy,
-					   IEEE1284_MODE_COMPAT))
+		if (parport_daisy_select(port, dev->daisy,
+					 IEEE1284_MODE_COMPAT))
 			port->daisy = dev->daisy;
 	}
 #endif /* IEEE1284.3 support */
--
2.47.3


             reply	other threads:[~2026-06-24  1:37 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-06-24  1:36 Yang Shao [this message]
2026-07-27  7:00 ` Yang Shao
2026-07-27 13:59   ` Marko Kohtala

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