staging: r8188eu: Remove goto to no-op exit label

PATCH In review Fabio M. De Francesco 4 participants 6 messages Apr 1, 2022 – Apr 4, 2022 Staging

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Fabio M. De Francesco

author

2022-04-01 18:35 UTC #0 lore raw

PATCH 1/1 staging: r8188eu: Remove goto to no-op exit label

In function rtw_free_netdev() there are two "goto" jumps to a no-op exit label called "RETURN". Remove the label and return in line.

Signed-off-by Fabio M. De Francesco <[email protected]>

---
 drivers/staging/r8188eu/os_dep/osdep_service.c | 7 ++-----
 1 file changed, 2 insertions(+), 5 deletions(-)

drivers/staging/r8188eu/os_dep/osdep_service.c +2 -5

index 7a6fcc96081a..d680bfba7f5d 100644
@@ -117,18 +117,15 @@ void rtw_free_netdev(struct net_device *netdev)
 	struct rtw_netdev_priv_indicator *pnpi;
 
 	if (!netdev)
-		goto RETURN;
+		return;
 
 	pnpi = netdev_priv(netdev);
 
 	if (!pnpi->priv)
-		goto RETURN;
+		return;
 
 	vfree(pnpi->priv);
 	free_netdev(netdev);
-
-RETURN:
-	return;
 }
 
 int rtw_change_ifname(struct adapter *padapter, const char *ifname)

Signature · 1 line

2.34.1

Ira Weiny

2022-04-01 20:41 UTC #1 lore raw

Quoted 2 lines · Fabio M. De Francesco

In function rtw_free_netdev() there are two "goto" jumps to a no-op exit label called "RETURN". Remove the label and return in line.

Thanks for the patch! However, A good commit message lists the why and what of a change. I don't see a why for this commit?

FWIW (For what it's worth) I know of a couple of good reasons for this change but you should get in the habit of putting that in the commit message. Even for obvious things like this.

Anyway, I think this patch can stand on it's own with an updated commit message. However, see below...

Quoted 12 lines

Signed-off-by Fabio M. De Francesco <[email protected]>

---
 drivers/staging/r8188eu/os_dep/osdep_service.c | 7 ++-----
 1 file changed, 2 insertions(+), 5 deletions(-)

drivers/staging/r8188eu/os_dep/osdep_service.c +0 -0

index 7a6fcc96081a..d680bfba7f5d 100644
@@ -117,18 +117,15 @@ void rtw_free_netdev(struct net_device *netdev)
 	struct rtw_netdev_priv_indicator *pnpi;

drivers/staging/r8188eu/os_dep/osdep_service.c void rtw_free_netdev(struct net_device *netdev) · line 125

Quoted 10 lines

drivers/staging/r8188eu/os_dep/osdep_service.c +2 -2

 
 	if (!netdev)
-		goto RETURN;
+		return;
 
 	pnpi = netdev_priv(netdev);
 
 	if (!pnpi->priv)
-		goto RETURN;
+		return;

This does not look right. If netdev is not NULL why does this function skip free_netdev()?

Fabio could you follow up with Larry and/or Phillip and see why the code does this? To me it looks like a potential bug.

Thanks!
Ira

Quoted 12 lines

drivers/staging/r8188eu/os_dep/osdep_service.c +0 -3

 	vfree(pnpi->priv);
 	free_netdev(netdev);
-
-RETURN:
-	return;
 }
 
 int rtw_change_ifname(struct adapter *padapter, const char *ifname)

Signature · 1 line

2.34.1

Fabio M. De Francesco

author

2022-04-02 10:13 UTC #2 lore raw

Quoted 6 lines · On venerd? 1 aprile 2022 22:41:40 CEST Ira Weiny wrote:

Quoted 2 lines · Fabio M. De Francesco
In function rtw_free_netdev() there are two "goto" jumps to a no-op exit label called "RETURN". Remove the label and return in line.
Thanks for the patch! However, A good commit message lists the why and what of a change. I don't see a why for this commit?

Yes I forgot the "why" :(
I'll rework the commit message for v2.

Quoted 21 lines

FWIW (For what it's worth) I know of a couple of good reasons for this change but you should get in the habit of putting that in the commit message. Even for obvious things like this.
Anyway, I think this patch can stand on it's own with an updated commit message. However, see below...
Quoted 13 lines
Signed-off-by Fabio M. De Francesco <[email protected]>
---
 drivers/staging/r8188eu/os_dep/osdep_service.c | 7 ++-----
 1 file changed, 2 insertions(+), 5 deletions(-)
drivers/staging/r8188eu/os_dep/osdep_service.c +0 -0
index 7a6fcc96081a..d680bfba7f5d 100644
@@ -117,18 +117,15 @@ void rtw_free_netdev(struct net_device *netdev)
 	struct rtw_netdev_priv_indicator *pnpi;
 

Quoted 3 lines

drivers/staging/r8188eu/os_dep/osdep_service.c void rtw_free_netdev(struct net_device *netdev) · line 120
Quoted 3 lines
drivers/staging/r8188eu/os_dep/osdep_service.c +1 -1
 	if (!netdev)
-		goto RETURN;
+		return;

Actually this function doesn't need to test for a valid "netdev". There are only two callers of this function (they are in os_dep/usb_intf.c) and they already test the pointer soon before calling rtw_free_netdev().

Therefore, I'll remove the test for a valid "netdev" and (obviously) the code has no more need to return at that point in function.

Quoted 6 lines

drivers/staging/r8188eu/os_dep/osdep_service.c void rtw_free_netdev(struct net_device *netdev) · line 125
Quoted 6 lines
drivers/staging/r8188eu/os_dep/osdep_service.c +1 -1
 	pnpi = netdev_priv(netdev);
 
 	if (!pnpi->priv)
-		goto RETURN;
+		return;

I cannot see how pnpi->priv might ever be NULL. Pavel Skripkin made me notice that "in rtw_alloc_etherdev() (I can confirm this information because now I've just read the code), if pnpi->priv allocation fails, then netdev will be just freed.". If "netdev" is already free, this function is never called.

Therefore, I'll remove this test too.

Quoted 2 lines

This does not look right. If netdev is not NULL why does this function skip free_netdev()?

After the two removals I've talked about above, the code will always call vfree(pnpi->priv) and then free_netdev(netdev).

Therefore, the code won't anymore skip free_netdev() and the bug is avoided.

Quoted 15 lines

Fabio could you follow up with Larry and/or Phillip and see why the code does this? To me it looks like a potential bug.
Thanks!
Ira
Quoted 8 lines
drivers/staging/r8188eu/os_dep/osdep_service.c +0 -3
 	vfree(pnpi->priv);
 	free_netdev(netdev);
-
-RETURN:
-	return;
 }
 

Quoted 5 lines

Quoted 4 lines
drivers/staging/r8188eu/os_dep/osdep_service.c +0 -0
 int rtw_change_ifname(struct adapter *padapter, const char *ifname)
Signature · 1 line
2.34.1

This is how I think to rework rtw_free_netdev():

void rtw_free_netdev(struct net_device *netdev)

{
        struct rtw_netdev_priv_indicator *pnpi = netdev_priv(netdev);

        vfree(pnpi->priv);
        free_netdev(netdev);
}

Am I missing something?

@Greg: please discard this patch; I'll send another that has the purpose to rework rtw_free_netdev() as I showed above for the purpose to avoid redundant tests and avoid the potential skipping of free_netdev() (as Ira has correctly noted, currently we have a bug).

Thanks,

Fabio

Martin Kaiser

2022-04-02 11:45 UTC #3 lore raw

Thus wrote Fabio M. De Francesco ([email protected]):

Quoted 7 lines

Quoted 5 lines
drivers/staging/r8188eu/os_dep/osdep_service.c void rtw_free_netdev(struct net_device *netdev) · line 125
Quoted 5 lines
drivers/staging/r8188eu/os_dep/osdep_service.c +1 -1
 	pnpi = netdev_priv(netdev);
 
 	if (!pnpi->priv)
-		goto RETURN;
+		return;
I cannot see how pnpi->priv might ever be NULL.

Even if pnpi->priv was NULL, we wouldn't need the check. It's ok to call vfree(NULL).

Quoted 2 lines

After the two removals I've talked about above, the code will always call vfree(pnpi->priv) and then free_netdev(netdev).

That makes sense.

Best regards,
Martin

Fabio M. De Francesco

author

2022-04-02 13:22 UTC #4 lore raw

Quoted 13 lines · On sabato 2 aprile 2022 13:45:33 CEST Martin Kaiser wrote:

Thus wrote Fabio M. De Francesco ([email protected]):
Quoted 7 lines
Quoted 5 lines
drivers/staging/r8188eu/os_dep/osdep_service.c void rtw_free_netdev(struct net_device *netdev) · line 125
Quoted 5 lines
drivers/staging/r8188eu/os_dep/osdep_service.c +1 -1
 	pnpi = netdev_priv(netdev);
 
 	if (!pnpi->priv)
-		goto RETURN;
+		return;
I cannot see how pnpi->priv might ever be NULL.
Even if pnpi->priv was NULL, we wouldn't need the check. It's ok to call vfree(NULL).

Quoted 8 lines

Quoted 2 lines
After the two removals I've talked about above, the code will always call vfree(pnpi->priv) and then free_netdev(netdev).
That makes sense.
Best regards,
Martin

Hi Martin,

Thanks for reminding to me that a vfree() on a NULL pointer is a no-op. I'm going to submit a new patch with the purpose to re-work rtw_free_netdev().

Thanks again,

Fabio

Dan Carpenter

2022-04-04 10:00 UTC #5 lore raw

In reply to Ira Weiny

Quoted 6 lines · Ira Weiny

Quoted 2 lines · Fabio M. De Francesco
In function rtw_free_netdev() there are two "goto" jumps to a no-op exit label called "RETURN". Remove the label and return in line.
Thanks for the patch! However, A good commit message lists the why and what of a change. I don't see a why for this commit?

People, stop belly aching about commit messages.

"Delete no-op goto" is sufficient justification.

regards,
dan carpenter