kern/174213: [fed] OFED sysfs/sysctl compat does not handle show/set attribute functions
Garrett Cooper
yanegomi at gmail.com
Thu Dec 13 06:00:01 UTC 2012
The following reply was made to PR kern/174213; it has been noted by GNATS.
From: Garrett Cooper <yanegomi at gmail.com>
To: bug-followup at FreeBSD.org, accornehl at gmail.com
Cc:
Subject: Re: kern/174213: [fed] OFED sysfs/sysctl compat does not handle
show/set attribute functions
Date: Wed, 12 Dec 2012 21:50:05 -0800 (PST)
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The attached patch fixes the issue and with the directions I
discussed on the mailing list, allowed me to flip between eth(ernet) mode
and ib mode.
Thanks!
-Garrett
From 53d4589061fe5c0dbcb3b58c3bcbb25fb212585a Mon Sep 17 00:00:00 2001
From: Garrett Cooper <yanegomi at gmail.com>
Date: Tue, 11 Dec 2012 22:10:00 -0800
Subject: [PATCH] Make the ofed sysctl<->sysfs handler more linux-like and
optimize it
Highlights:
The previous code was incorrectly assuming that sysfs and sysctls have a
1:1 relationship, but sysfs on Linux based on the documentation I've
found (and the Linux driver / example code I've peeked at) assumes
there's a trailing newline at the end of each value; so we need to
append a newline to the sysctl buffer on store and remove it on show in
order to be properly compatible between sysctl(9) and sysfs.
Also, the wrong value was being passed into SYSCTL_IN (PAGE_SIZE). It
should have been req->newlen.
Lowlights:
1. Many of the error conditions could have been simplified up-front
(dealing with checking the kobj object and whether or not buf was
NULL).
2. buf was being leaked if the kobj object was invalid.
3. The code now allows the user to store and show, store and not show,
or show and not store.
The issues highlighted address kern/174213.
Sponsored-by: EMC Corporation
Signed-off-by: Garrett Cooper <yanegomi at gmail.com>
---
sys/ofed/include/linux/sysfs.h | 53 ++++++++++++++++++++++++++++--------------
1 file changed, 35 insertions(+), 18 deletions(-)
diff --git a/sys/ofed/include/linux/sysfs.h b/sys/ofed/include/linux/sysfs.h
index 698f75e..1aff3c2 100644
--- a/sys/ofed/include/linux/sysfs.h
+++ b/sys/ofed/include/linux/sysfs.h
@@ -69,6 +69,10 @@ struct attribute_group {
* a constant string: point arg1 at it, arg2 is zero.
*/
+/*
+ * XXX: should support iteration of pages as sysfs supports paging
+ * in/paging out data in PAGE_SIZE chunks.
+ */
static inline int
sysctl_handle_attr(SYSCTL_HANDLER_ARGS)
{
@@ -76,37 +80,50 @@ sysctl_handle_attr(SYSCTL_HANDLER_ARGS)
struct attribute *attr;
const struct sysfs_ops *ops;
void *buf;
- int error;
ssize_t len;
+ int error = 0;
kobj = arg1;
attr = (struct attribute *)arg2;
- buf = (void *)get_zeroed_page(GFP_KERNEL);
- len = 1; /* Copy out a NULL byte at least. */
if (kobj->ktype == NULL || kobj->ktype->sysfs_ops == NULL)
return (ENODEV);
- ops = kobj->ktype->sysfs_ops;
+ buf = (void *)get_zeroed_page(GFP_KERNEL);
if (buf == NULL)
return (ENOMEM);
- if (ops->show) {
- len = ops->show(kobj, attr, buf);
- /*
- * It's valid not to have a 'show' so we just return 1 byte
- * of NULL.
- */
- if (len < 0) {
- error = -len;
- len = 1;
- if (error != EIO)
- goto out;
- }
+ ops = kobj->ktype->sysfs_ops;
+
+ /* Show */
+ if (ops->show == NULL)
+ goto store;
+ len = ops->show(kobj, attr, buf);
+ if (len < 0) {
+ error = -len;
+ len = 1;
+ if (error != EIO)
+ goto out;
}
+ /* It's valid not to have a 'show' so we just return NUL. */
+ else if (len == 0)
+ len = 1;
+ len -= 1;
+ ((char*)buf)[len] = '\0';
error = SYSCTL_OUT(req, buf, len);
- if (error || !req->newptr || ops->store == NULL)
+ if (error)
+ goto out;
+
+store:
+ /* Store */
+ if (!req->newptr || ops->store == NULL)
+ goto out;
+ if (req->newlen > PAGE_SIZE-2) { /* NUL terminated + '\n' */
+ error = EINVAL;
goto out;
- error = SYSCTL_IN(req, buf, PAGE_SIZE);
+ }
+ error = SYSCTL_IN(req, buf, req->newlen);
if (error)
goto out;
+ ((char*)buf)[req->newlen] = '\n';
+ ((char*)buf)[req->newlen+1] = '\0';
len = ops->store(kobj, attr, buf, req->newlen);
if (len < 0)
error = -len;
--
1.8.0.1
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