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wireless: rtl8187: replace udev with usb_get_dev()

PATCH In review Salah Triki 4 participants 4 messages Jul 24, 2021 – Jul 27, 2021 1 message not in the archive

Subsystems (3)
Networking Network drivers RTL8187 wireless driver
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Salah Triki

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#0 lore raw

PATCH 1/1 wireless: rtl8187: replace udev with usb_get_dev()

Replace udev with usb_get_dev() in order to make code cleaner.

Signed-off-by Salah Triki <[email protected]>
---
 drivers/net/wireless/realtek/rtl818x/rtl8187/dev.c | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)
drivers/net/wireless/realtek/rtl818x/rtl8187/dev.c +1 -3
index eb68b2d3caa1..30bb3c2b8407 100644
@@ -1455,9 +1455,7 @@ static int rtl8187_probe(struct usb_interface *intf,
 
 	SET_IEEE80211_DEV(dev, &intf->dev);
 	usb_set_intfdata(intf, dev);
-	priv->udev = udev;
-
-	usb_get_dev(udev);
+	priv->udev = usb_get_dev(udev);
 
 	skb_queue_head_init(&priv->rx_queue);
Signature · 1 line
2.25.1

A message that is not in the archive (sent off-list or not yet received): [email protected]

#2 lore raw
Quoted 25 lines · Hin-Tak Leung
Quoted 19 lines · Salah Triki

Replace udev with usb_get_dev() in order to make code cleaner.

Signed-off-by Salah Triki <[email protected]>

---
drivers/net/wireless/realtek/rtl818x/rtl8187/dev.c | 4 +---

1 file changed, 1 insertion(+), 3 deletions(-)
drivers/net/wireless/realtek/rtl818x/rtl8187/dev.c +1 -3
index eb68b2d3caa1..30bb3c2b8407 100644
@@ -1455,9 +1455,7 @@ static int rtl8187_probe(struct usb_interface *intf,
 
     SET_IEEE80211_DEV(dev, &intf->dev);
     usb_set_intfdata(intf, dev);
-    priv->udev = udev;
-
-    usb_get_dev(udev);
+    priv->udev = usb_get_dev(udev);
Quoted 7 lines
Quoted 4 lines
drivers/net/wireless/realtek/rtl818x/rtl8187/dev.c +0 -0
     skb_queue_head_init(&priv->rx_queue);
Signature · 1 line
2.25.1

It is not cleaner - the change is not functionally equivalent. Before the change, the reference count is increased after the assignment; and after the change, before the assignment. So my question is, does the reference count increasing a little earlier matters? What can go wrong between very short time where the reference count increases, and priv->udev not yet assigned? I think there might be a race condition where the probbe function is called very shortly twice. Especially if the time of running the reference count function is non-trivial.

Probe functions are called in order, this should not be an issue.

This patch changes nothing, I do not think it is needed at all.

thanks,

greg k-h

#3 lore raw
In reply to a message not in the archive
Quoted 28 lines · Hin-Tak Leung

Review

Quoted 8 lines · Salah Triki

Replace udev with usb_get_dev() in order to make code cleaner.

Signed-off-by Salah Triki <[email protected]>

---
drivers/net/wireless/realtek/rtl818x/rtl8187/dev.c | 4 +---

1 file changed, 1 insertion(+), 3 deletions(-)
(quoted diff) +0 -0

b/drivers/net/wireless/realtek/rtl818x/rtl8187/dev.c

Quoted 13 lines

index eb68b2d3caa1..30bb3c2b8407 100644

drivers/net/wireless/realtek/rtl818x/rtl8187/dev.c +1 -3
@@ -1455,9 +1455,7 @@ static int rtl8187_probe(struct usb_interface *intf,
 
     SET_IEEE80211_DEV(dev, &intf->dev);
     usb_set_intfdata(intf, dev);
-    priv->udev = udev;
-
-    usb_get_dev(udev);
+    priv->udev = usb_get_dev(udev);
 
     skb_queue_head_init(&priv->rx_queue);
Quoted 7 lines
Quoted 2 lines
drivers/net/wireless/realtek/rtl818x/rtl8187/dev.c +0 -1
--

2.25.1

It is not cleaner - the change is not functionally equivalent. Before the change, the reference count is increased after the assignment; and after the change, before the assignment. So my question is, does the reference count increasing a little earlier matters? What can go wrong between very short time where the reference count increases, and priv->udev not yet assigned? I think there might be a race condition where the probbe function is called very shortly twice. Especially if the time of running the reference count function is non-trivial.

Larry, what do you think?

My belief was that probe routines were called in order, which was confirmed by GregKH. As a result, there can be no race condition, and the order of setting the reference count does not matter. On the other hand, the current code is not misleading, nor unclear. Why should it be changed?

NACK on the patch.

Larry

#4 lore raw
In reply to a message not in the archive
Quoted 37 lines · Hin-Tak Leung

Review

Quoted 8 lines · Salah Triki

Replace udev with usb_get_dev() in order to make code cleaner.

Signed-off-by Salah Triki <[email protected]>

---
drivers/net/wireless/realtek/rtl818x/rtl8187/dev.c | 4 +---

1 file changed, 1 insertion(+), 3 deletions(-)
(quoted diff) +0 -0

b/drivers/net/wireless/realtek/rtl818x/rtl8187/dev.c

Quoted 16 lines

index eb68b2d3caa1..30bb3c2b8407 100644

drivers/net/wireless/realtek/rtl818x/rtl8187/dev.c +1 -3
@@ -1455,9 +1455,7 @@ static int rtl8187_probe(struct usb_interface *intf,
 
    SET_IEEE80211_DEV(dev, &intf->dev);
    usb_set_intfdata(intf, dev);
-    priv->udev = udev;
-
-    usb_get_dev(udev);
+    priv->udev = usb_get_dev(udev);
 
    skb_queue_head_init(&priv->rx_queue);
Signature · 1 line
2.25.1

It is not cleaner - the change is not functionally equivalent. Before the change, the reference count is increased after the assignment; and after the change, before the assignment. So my question is, does the reference count increasing a little earlier matters? What can go wrong between very short time where the reference count increases, and priv->udev not yet assigned? I think there might be a race condition where the probbe function is called very shortly twice. Especially if the time of running the reference count function is non-trivial.

Quoted 1 line

Larry, what do you think?

BTW, please don't use HTML in emails. Our lists drop all HTML mail (and for a good reason).

Signature · 3 lines
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