Re: [RFC] MODALIAS support for SCSI devices (try 1)

From: Andrey Borzenkov
Date: Tue Jul 04 2006 - 17:43:11 EST

Michael Tokarev wrote:

> The following patch adds support for sysfs/uevent modalias
> attribute for scsi devices (like disks, tapes, cdroms etc),
> based on whatever current sd.c, sr.c, st.c and osst.c drivers
> supports.
>

So I was not the only one to get this idea :)

> The modalias format is like this:
>
> scsi:type-0x04
>
> (for TYPE_WORM, handled by sr.c now).
>
> Several comments.
>
> o This hexadecimal type value is because all TYPE_XXX constants
> in include/scsi/scsi.h are given in hex, but __stringify() will
> not convert them to decimal (so it will NOT be scsi:type-4).
> Since it does not really matter in which format it is, while
> both modalias in module and modalias attribute match each other,
> I descided to go for that 0x%02x format (and added a comment in
> include/scsi/scsi.h to keep them that way), instead of changing
> them all to decimal.
>


well, I started with the same but then changed my mind.

- is it possible that in future some more information may be added? Like
vendor ID, product ID or whatever? At least in one case SCSI type is not
enough to distinguish between drivers (st vs. osst Onstream tapes).

- it makes sense to redo bus matching then; which requires some sort of
explicit ID table anyway.

Unfortunately I do not have the patch ready as yet; may be end of week.

> o There was no .uevent routine for SCSI bus. It might be a good
> idea to add some more ueven environment variables in there.
>
> o osst.c driver handles tapes too, like st.c, but only SOME tapes.
> With this setup, hotplug scripts (or whatever is used by the
> user) will try to load both st and osst modules for all SCSI
> tapes found, because both modules have scsi:type-0x01 alias).
> It is not harmful, but one extra module is no good either.
> It is possible to solve this, by exporting more info in
> modalias attribute, including vendor and device identification
> strings, so that modalias becomes something like
> scsi:type-0x12:vendor-Adaptec LTD:device-OnStream Tape Drive
> and having that, match for all 3 attributes, not only device
> type. But oh well, vendor and device strings may be large,
> and they do contain spaces and whatnot.
> So I left them for now, awaiting for comments first.
>

We can go the PCMCIA way that stores string hashes; like in

Identification: manf_id: 0x0156 card_id: 0x0002
function: 6 (network)
prod_id(1): "TOSHIBA" (0xb4585a1a)
prod_id(2): "Wireless LAN Card" (0x0b537c13)
prod_id(3): "Version 01.01" (0xd27deb1a)
prod_id(4): --- (---)

strictly speaking, modalias real value is not relevant, we are going to
do "modprobe $modalias" anyway without even looking at it.

-andrey

> The patch is against 2.6.17, but should apply to more recent
> versions as well.
>
> And oh, almost forget:
>
> Signed-Off-By: Michael Tokarev <mjt@xxxxxxxxxx>
>
> Thanks.
>
> --- linux-2.6.17.orig/drivers/scsi/osst.c 2006-06-18 05:49:35.000000000
> +0400
> +++ linux-2.6.17/drivers/scsi/osst.c 2006-07-04 22:59:18.000000000 +0400
> @@ -87,6 +87,7 @@ MODULE_AUTHOR("Willem Riede");
> MODULE_DESCRIPTION("OnStream {DI-|FW-|SC-|USB}{30|50} Tape Driver");
> MODULE_LICENSE("GPL");
> MODULE_ALIAS_CHARDEV_MAJOR(OSST_MAJOR);
> +MODULE_ALIAS_SCSI_DEVICE(TYPE_TAPE);
>
> module_param(max_dev, int, 0444);
> MODULE_PARM_DESC(max_dev, "Maximum number of OnStream Tape Drives to
> attach (4)");
> --- linux-2.6.17.orig/drivers/scsi/scsi_sysfs.c 2006-06-18
> 05:49:35.000000000 +0400
> +++ linux-2.6.17/drivers/scsi/scsi_sysfs.c 2006-07-05 00:16:17.000000000
> +0400 @@ -275,6 +275,19 @@ static int scsi_bus_match(struct device
> return (sdp->inq_periph_qual == SCSI_INQ_PQ_CON)? 1: 0;
> }
>
> +static int scsi_bus_uevent(struct device *dev, char **envp, int num_envp,
> + char *buffer, int buffer_size)
> +{
> + struct scsi_device *sdev = to_scsi_device(dev);
> + int i = 0;
> + int length = 0;
> +
> + add_uevent_var(envp, num_envp, &i, buffer, buffer_size, &length,
> + "MODALIAS=" SCSI_DEVICE_MODALIAS_FMT, sdev->type);
> + envp[i] = NULL;
> + return 0;
> +}
> +
> static int scsi_bus_suspend(struct device * dev, pm_message_t state)
> {
> struct scsi_device *sdev = to_scsi_device(dev);
> @@ -307,6 +320,7 @@ static int scsi_bus_resume(struct device
> struct bus_type scsi_bus_type = {
> .name = "scsi",
> .match = scsi_bus_match,
> + .uevent = scsi_bus_uevent,
> .suspend = scsi_bus_suspend,
> .resume = scsi_bus_resume,
> };
> @@ -534,6 +548,14 @@ show_sdev_iostat(iorequest_cnt);
> show_sdev_iostat(iodone_cnt);
> show_sdev_iostat(ioerr_cnt);
>
> +static ssize_t
> +sdev_show_modalias(struct device *dev, struct device_attribute *attr,
> char *buf) +{
> + struct scsi_device *sdev;
> + sdev = to_scsi_device(dev);
> + return snprintf (buf, 20, SCSI_DEVICE_MODALIAS_FMT "\n", sdev->type);
> +}
> +static DEVICE_ATTR(modalias, S_IRUGO, sdev_show_modalias, NULL);
>
> /* Default template for device attributes. May NOT be modified */
> static struct device_attribute *scsi_sysfs_sdev_attrs[] = {
> @@ -553,6 +575,7 @@ static struct device_attribute *scsi_sys
> &dev_attr_iorequest_cnt,
> &dev_attr_iodone_cnt,
> &dev_attr_ioerr_cnt,
> + &dev_attr_modalias,
> NULL
> };
>
> --- linux-2.6.17.orig/drivers/scsi/sd.c 2006-06-18 05:49:35.000000000
> +0400
> +++ linux-2.6.17/drivers/scsi/sd.c 2006-07-04 22:53:29.000000000 +0400
> @@ -90,6 +90,9 @@ MODULE_ALIAS_BLOCKDEV_MAJOR(SCSI_DISK12_
> MODULE_ALIAS_BLOCKDEV_MAJOR(SCSI_DISK13_MAJOR);
> MODULE_ALIAS_BLOCKDEV_MAJOR(SCSI_DISK14_MAJOR);
> MODULE_ALIAS_BLOCKDEV_MAJOR(SCSI_DISK15_MAJOR);
> +MODULE_ALIAS_SCSI_DEVICE(TYPE_DISK);
> +MODULE_ALIAS_SCSI_DEVICE(TYPE_MOD);
> +MODULE_ALIAS_SCSI_DEVICE(TYPE_RBC);
>
> /*
> * This is limited by the naming scheme enforced in sd_probe,
> --- linux-2.6.17.orig/drivers/scsi/sr.c 2006-06-18 05:49:35.000000000
> +0400
> +++ linux-2.6.17/drivers/scsi/sr.c 2006-07-04 22:54:49.000000000 +0400
> @@ -63,6 +63,8 @@
> MODULE_DESCRIPTION("SCSI cdrom (sr) driver");
> MODULE_LICENSE("GPL");
> MODULE_ALIAS_BLOCKDEV_MAJOR(SCSI_CDROM_MAJOR);
> +MODULE_ALIAS_SCSI_DEVICE(TYPE_ROM);
> +MODULE_ALIAS_SCSI_DEVICE(TYPE_WORM);
>
> #define SR_DISKS 256
>
> --- linux-2.6.17.orig/drivers/scsi/st.c 2006-06-18 05:49:35.000000000
> +0400
> +++ linux-2.6.17/drivers/scsi/st.c 2006-07-04 22:56:02.000000000 +0400
> @@ -89,6 +89,7 @@ MODULE_AUTHOR("Kai Makisara");
> MODULE_DESCRIPTION("SCSI tape (st) driver");
> MODULE_LICENSE("GPL");
> MODULE_ALIAS_CHARDEV_MAJOR(SCSI_TAPE_MAJOR);
> +MODULE_ALIAS_SCSI_DEVICE(TYPE_TAPE);
>
> /* Set 'perm' (4th argument) to 0 to disable module_param's definition
> * of sysfs parameters (which module_param doesn't yet support).
> --- linux-2.6.17.orig/include/scsi/scsi_device.h 2006-06-18
> 05:49:35.000000000 +0400
> +++ linux-2.6.17/include/scsi/scsi_device.h 2006-07-05 00:16:40.000000000
> +0400 @@ -352,4 +352,9 @@ static inline int scsi_device_qas(struct
> return 0;
> return sdev->inquiry[56] & 0x02;
> }
> +
> +#define MODULE_ALIAS_SCSI_DEVICE(type) \
> + MODULE_ALIAS("scsi:t-" __stringify(type) "*")
> +#define SCSI_DEVICE_MODALIAS_FMT "scsi:t-0x%02x"
> +
> #endif /* _SCSI_SCSI_DEVICE_H */
> --- linux-2.6.17.orig/include/scsi/scsi.h 2006-06-18 05:49:35.000000000
> +0400
> +++ linux-2.6.17/include/scsi/scsi.h 2006-07-04 22:35:53.000000000 +0400
> @@ -207,6 +207,7 @@ static inline int scsi_status_is_good(in
>
> /*
> * DEVICE TYPES
> + * Please keep them in 0x%02x format for $MODALIAS to work
> */
>
> #define TYPE_DISK 0x00
> -
> To unsubscribe from this list: send the line "unsubscribe linux-scsi" in
> the body of a message to majordomo@xxxxxxxxxxxxxxx
> More majordomo info at http://vger.kernel.org/majordomo-info.html


-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/