[PATCH] modpost: i2c aliases need no trailing wildcard

[PATCH] modpost: i2c aliases need no trailing wildcard

[Jean Delvare]

Hi all,

[Once more with Sam's address fixed, sorry for the noise.]

Not all device types need a wildcard at the end of their module
aliases. In particular, for i2c module aliases, the trailing wildcard
is not only unneeded, it could also cause the wrong driver to be
loaded.

As I2C devices have no IDs, i2c module aliases are simple, arbitrary
device names. For example:

$ /sbin/modinfo lm90
filename:       /lib/modules/2.6.25-git18/kernel/drivers/hwmon/lm90.ko
author:         Jean Delvare <khali@linux-fr.org>
description:    LM90/ADM1032 driver
license:        GPL
vermagic:       2.6.25-git18 mod_unload
depends:        hwmon
alias:          i2c:lm90*
alias:          i2c:adm1032*
alias:          i2c:lm99*
alias:          i2c:lm86*
alias:          i2c:max6657*
alias:          i2c:adt7461*
alias:          i2c:max6680*
$

This would cause trouble if one I2C chip name matches the beginning of
another I2C chip name and both chips are supported by different
drivers. For example, an i2c device named lm9042 would cause the lm90
driver to be loaded, while it doesn't support that device. This case
has yet to be seen in practice, but still, I'd like to fix it now. The
cleanest fix is to remove the trailing wildcard from i2c module aliases.

Here's a patch doing this. If nobody objects, I'll send it to Linus
through my i2c tree next week.

* * * * *

Not all device type aliases need a trailing wildcard, in particular
the i2c aliases don't. Don't add a wildcard by default in do_table(),
instead let each device type handler add it if needed.

Signed-off-by: Jean Delvare <khali@linux-fr.org>
---
I have tested types acpi, dmi, eisa, i2c, ide, ieee1394, input, pci,
pcmcia, platform, pnp, scsi, serio, ssb and usb. Other types (ccw, of,
vio, parisc, sdio and virtio) are untested.

 scripts/mod/file2alias.c |   35 ++++++++++++++++++++++++++---------
 1 file changed, 26 insertions(+), 9 deletions(-)

--- linux-2.6.26-rc0.orig/scripts/mod/file2alias.c	2008-05-02 18:37:38.000000000 +0200
+++ linux-2.6.26-rc0/scripts/mod/file2alias.c	2008-05-02 20:23:07.000000000 +0200
@@ -51,6 +51,15 @@ do {                                    
                 sprintf(str + strlen(str), "*");                \
 } while(0)
 
+/* Always end in a wildcard, for future extension */
+static inline void add_wildcard(char *str)
+{
+	int len = strlen(str);
+
+	if (str[len - 1] != '*')
+		strcat(str + len, "*");
+}
+
 unsigned int cross_build = 0;
 /**
  * Check that sizeof(device_id type) are consistent with size of section
@@ -133,9 +142,7 @@ static void do_usb_entry(struct usb_devi
 	    id->match_flags&USB_DEVICE_ID_MATCH_INT_PROTOCOL,
 	    id->bInterfaceProtocol);
 
-	/* Always end in a wildcard, for future extension */
-	if (alias[strlen(alias)-1] != '*')
-		strcat(alias, "*");
+	add_wildcard(alias);
 	buf_printf(&mod->dev_table_buf,
 		   "MODULE_ALIAS(\"%s\");\n", alias);
 }
@@ -219,6 +226,7 @@ static int do_ieee1394_entry(const char 
 	ADD(alias, "ver", id->match_flags & IEEE1394_MATCH_VERSION,
 	    id->version);
 
+	add_wildcard(alias);
 	return 1;
 }
 
@@ -261,6 +269,7 @@ static int do_pci_entry(const char *file
 	ADD(alias, "bc", baseclass_mask == 0xFF, baseclass);
 	ADD(alias, "sc", subclass_mask == 0xFF, subclass);
 	ADD(alias, "i", interface_mask == 0xFF, interface);
+	add_wildcard(alias);
 	return 1;
 }
 
@@ -283,6 +292,7 @@ static int do_ccw_entry(const char *file
 	    id->dev_type);
 	ADD(alias, "dm", id->match_flags&CCW_DEVICE_ID_MATCH_DEVICE_MODEL,
 	    id->dev_model);
+	add_wildcard(alias);
 	return 1;
 }
 
@@ -290,7 +300,7 @@ static int do_ccw_entry(const char *file
 static int do_ap_entry(const char *filename,
 		       struct ap_device_id *id, char *alias)
 {
-	sprintf(alias, "ap:t%02X", id->dev_type);
+	sprintf(alias, "ap:t%02X*", id->dev_type);
 	return 1;
 }
 
@@ -309,6 +319,7 @@ static int do_serio_entry(const char *fi
 	ADD(alias, "id", id->id != SERIO_ANY, id->id);
 	ADD(alias, "ex", id->extra != SERIO_ANY, id->extra);
 
+	add_wildcard(alias);
 	return 1;
 }
 
@@ -316,7 +327,7 @@ static int do_serio_entry(const char *fi
 static int do_acpi_entry(const char *filename,
 			struct acpi_device_id *id, char *alias)
 {
-	sprintf(alias, "acpi*:%s:", id->id);
+	sprintf(alias, "acpi*:%s:*", id->id);
 	return 1;
 }
 
@@ -324,7 +335,7 @@ static int do_acpi_entry(const char *fil
 static int do_pnp_entry(const char *filename,
 			struct pnp_device_id *id, char *alias)
 {
-	sprintf(alias, "pnp:d%s", id->id);
+	sprintf(alias, "pnp:d%s*", id->id);
 	return 1;
 }
 
@@ -409,6 +420,7 @@ static int do_pcmcia_entry(const char *f
        ADD(alias, "pc", id->match_flags & PCMCIA_DEV_ID_MATCH_PROD_ID3, id->prod_id_hash[2]);
        ADD(alias, "pd", id->match_flags & PCMCIA_DEV_ID_MATCH_PROD_ID4, id->prod_id_hash[3]);
 
+	add_wildcard(alias);
        return 1;
 }
 
@@ -432,6 +444,7 @@ static int do_of_entry (const char *file
         if (isspace (*tmp))
             *tmp = '_';
 
+    add_wildcard(alias);
     return 1;
 }
 
@@ -448,6 +461,7 @@ static int do_vio_entry(const char *file
 		if (isspace (*tmp))
 			*tmp = '_';
 
+	add_wildcard(alias);
 	return 1;
 }
 
@@ -511,6 +525,8 @@ static int do_eisa_entry(const char *fil
 {
 	if (eisa->sig[0])
 		sprintf(alias, EISA_DEVICE_MODALIAS_FMT "*", eisa->sig);
+	else
+		strcat(alias, "*");
 	return 1;
 }
 
@@ -529,6 +545,7 @@ static int do_parisc_entry(const char *f
 	ADD(alias, "rev", id->hversion_rev != PA_HVERSION_REV_ANY_ID, id->hversion_rev);
 	ADD(alias, "sv", id->sversion != PA_SVERSION_ANY_ID, id->sversion);
 
+	add_wildcard(alias);
 	return 1;
 }
 
@@ -544,6 +561,7 @@ static int do_sdio_entry(const char *fil
 	ADD(alias, "c", id->class != (__u8)SDIO_ANY_ID, id->class);
 	ADD(alias, "v", id->vendor != (__u16)SDIO_ANY_ID, id->vendor);
 	ADD(alias, "d", id->device != (__u16)SDIO_ANY_ID, id->device);
+	add_wildcard(alias);
 	return 1;
 }
 
@@ -559,6 +577,7 @@ static int do_ssb_entry(const char *file
 	ADD(alias, "v", id->vendor != SSB_ANY_VENDOR, id->vendor);
 	ADD(alias, "id", id->coreid != SSB_ANY_ID, id->coreid);
 	ADD(alias, "rev", id->revision != SSB_ANY_REV, id->revision);
+	add_wildcard(alias);
 	return 1;
 }
 
@@ -573,6 +592,7 @@ static int do_virtio_entry(const char *f
 	ADD(alias, "d", 1, id->device);
 	ADD(alias, "v", id->vendor != VIRTIO_DEV_ANY_ID, id->vendor);
 
+	add_wildcard(alias);
 	return 1;
 }
 
@@ -612,9 +632,6 @@ static void do_table(void *symval, unsig
 
 	for (i = 0; i < size; i += id_size) {
 		if (do_entry(mod->name, symval+i, alias)) {
-			/* Always end in a wildcard, for future extension */
-			if (alias[strlen(alias)-1] != '*')
-				strcat(alias, "*");
 			buf_printf(&mod->dev_table_buf,
 				   "MODULE_ALIAS(\"%s\");\n", alias);
 		}

-- 
Jean Delvare

Re: [i2c] [PATCH] modpost: i2c aliases need no trailing wildcard

[Jochen Friedrich]

Hi Jean,

> Here's a patch doing this. If nobody objects, I'll send it to Linus
> through my i2c tree next week.

looks good to me:

#cat modules.alias 
# Aliases extracted from modules themselves.
alias i2c:dbox2-fp dbox2_fp
alias of:N*T*Cfsl,cpm-i2c* i2c_cpm
alias i2c:dummy i2c_core
alias i2c:saa7129 saa7127
alias i2c:saa7128 saa7127
alias i2c:saa7127 saa7127
alias i2c:saa7126 saa7127

Thanks,
Jochen

Re: [PATCH] modpost: i2c aliases need no trailing wildcard

[Jean Delvare]

Hi Jochen,

On Sat, 03 May 2008 14:21:20 +0200, Jochen Friedrich wrote:
> Hi Jean,
> 
> > Here's a patch doing this. If nobody objects, I'll send it to Linus
> > through my i2c tree next week.
> 
> looks good to me:

Thanks for testing and reporting!

> #cat modules.alias 
> # Aliases extracted from modules themselves.
> alias i2c:dbox2-fp dbox2_fp
> alias of:N*T*Cfsl,cpm-i2c* i2c_cpm
> alias i2c:dummy i2c_core

I don't have this one, and I doubt it is really useful...

> alias i2c:saa7129 saa7127
> alias i2c:saa7128 saa7127
> alias i2c:saa7127 saa7127
> alias i2c:saa7126 saa7127

-- 
Jean Delvare

Re: [PATCH] modpost: i2c aliases need no trailing wildcard

[Sam Ravnborg]

On Fri, May 02, 2008 at 08:37:21PM +0200, Jean Delvare wrote:
> Hi all,
> 
> [Once more with Sam's address fixed, sorry for the noise.]
> 
> Not all device types need a wildcard at the end of their module
> aliases. In particular, for i2c module aliases, the trailing wildcard
> is not only unneeded, it could also cause the wrong driver to be
> loaded.
...
Hi Jean.

Do you expect me to take this via kbuild.git?

	Sam

Re: [PATCH] modpost: i2c aliases need no trailing wildcard

[Jean Delvare]

Hi Sam,

On Sat, 3 May 2008 20:04:20 +0200, Sam Ravnborg wrote:
> On Fri, May 02, 2008 at 08:37:21PM +0200, Jean Delvare wrote:
> > Hi all,
> > 
> > [Once more with Sam's address fixed, sorry for the noise.]
> > 
> > Not all device types need a wildcard at the end of their module
> > aliases. In particular, for i2c module aliases, the trailing wildcard
> > is not only unneeded, it could also cause the wrong driver to be
> > loaded.
> ...
> Hi Jean.
> 
> Do you expect me to take this via kbuild.git?

At your option. If it's easier for you to synchronize with other
patches possibly touching this file, please do. If not, I can push it
via my i2c tree. Just let me know.

-- 
Jean Delvare

Re: [PATCH] modpost: i2c aliases need no trailing wildcard

[Rusty Russell]

On Saturday 03 May 2008 04:37:21 Jean Delvare wrote:
> Hi all,
>
> [Once more with Sam's address fixed, sorry for the noise.]
>
> Not all device types need a wildcard at the end of their module
> aliases. In particular, for i2c module aliases, the trailing wildcard
> is not only unneeded, it could also cause the wrong driver to be
> loaded.

Hi Jean,

   i2c would have been better using a terminator char after the device name.  
The wildcard would then allow future extensions without having the current 
potential confusion.

Still, there's nothing wrong with this patch, happy for you to send it.

Acked-by: Rusty Russell <rusty@rustcorp.com.au>

Cheers,
Rusty.

Re: [PATCH] modpost: i2c aliases need no trailing wildcard

[Jean Delvare]

Hi Rusty,

On Mon, 5 May 2008 10:09:05 +1000, Rusty Russell wrote:
> On Saturday 03 May 2008 04:37:21 Jean Delvare wrote:
> > Hi all,
> >
> > [Once more with Sam's address fixed, sorry for the noise.]
> >
> > Not all device types need a wildcard at the end of their module
> > aliases. In particular, for i2c module aliases, the trailing wildcard
> > is not only unneeded, it could also cause the wrong driver to be
> > loaded.
> 
> Hi Jean,
> 
>    i2c would have been better using a terminator char after the device name.  
> The wildcard would then allow future extensions without having the current 
> potential confusion.

This has been discussed already:
http://lists.lm-sensors.org/pipermail/i2c/2008-April/003429.html

I understand that the idea of the trailing wildcard was to allow for
future extensions, however in the case of i2c I can't foresee any such
extension. On top of that, it really only matters for external drivers
(for in-tree drivers, if the alias format changes, the drivers will
also be updated so no harm done) and I don't think external drivers are
worth the effort and cost of anticipating a change which most certainly
will never happen.

> Still, there's nothing wrong with this patch, happy for you to send it.
> 
> Acked-by: Rusty Russell <rusty@rustcorp.com.au>

Thanks,
-- 
Jean Delvare

Re: [PATCH] modpost: i2c aliases need no trailing wildcard

[Sam Ravnborg]

> > Still, there's nothing wrong with this patch, happy for you to send it.
> > 
> > Acked-by: Rusty Russell <rusty@rustcorp.com.au>
> 
> Thanks,

The patch is in -linus already so I cannot add the "Acked-by".

	Sam

Re: [PATCH] modpost: i2c aliases need no trailing wildcard

[Rusty Russell]

On Monday 05 May 2008 19:09:29 Sam Ravnborg wrote:
> > > Still, there's nothing wrong with this patch, happy for you to send it.
> > >
> > > Acked-by: Rusty Russell <rusty@rustcorp.com.au>
> >
> > Thanks,
>
> The patch is in -linus already so I cannot add the "Acked-by".

Since the purpose is to ease passage into Linus' tree, it seems academic?

Cheers,
Rusty.