linux-kernel - Re: 2.6.19-rc3: known unfixed regressions (v3)

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Message-ID: <20061030135625.GB1601@mellanox.co.il>
Date:	Mon, 30 Oct 2006 15:56:26 +0200
From:	"Michael S. Tsirkin" <mst@...lanox.co.il>
To:	Pavel Machek <pavel@...e.cz>
Cc:	Adrian Bunk <bunk@...sta.de>, Linus Torvalds <torvalds@...l.org>,
	Andrew Morton <akpm@...l.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	len.brown@...el.com, linux-acpi@...r.kernel.org, linux-pm@...l.org,
	"Jun'ichi Nomura" <j-nomura@...jp.nec.com>,
	"Randy.Dunlap" <rdunlap@...otime.net>,
	Martin Lorenz <martin@...enz.eu.org>
Subject: Re: 2.6.19-rc3: known unfixed regressions (v3)

Quoting r. Adrian Bunk <bunk@...sta.de>:
> Subject    : T60 stops triggering any ACPI events
> References : http://lkml.org/lkml/2006/10/4/425
>              http://lkml.org/lkml/2006/10/16/262
>              http://bugzilla.kernel.org/show_bug.cgi?id=7408
> Submitter  : "Michael S. Tsirkin" <mst@...lanox.co.il>
> Status     : unknown

OK, I spent half a night with git-bisect, and the patch that triggers this issue
seems to be this:

commit d7dd8fd9557840162b724a8ac1366dd78a12dff
Author: Andrew Morton <akpm@...l.org> 
    [PATCH] blockdev.c: check driver layer errors

Reset to d7dd8fd9557840162b724a8ac1366dd78a12dff seems to hide part of the issue
(I have ACPI after kernel build, but not after suspend/resume).  Both reverting
this patch, and reset to the parent of this patch seem to solve (or at least,
hide) both problems for me (no ACPI after suspend/resume and no ACPI after
kernel build).

I am currently running on 2.6.19-rc3 minus
d7dd8fd9557840162b724a8ac1366dd78a12dff, and in a full day of use I have not
observed any issues yet. 2.6.19-rc3 without reverting
d7dd8fd9557840162b724a8ac1366dd78a12dff stops receiving ACPI events after some
use (sometimes after suspend/resume, sometimes after kernel build stress).  Now,
what does this tell us? Andrew, any idea?


Martin, could you test whether reverting this helps you, too, by chance?
Here's a patch to apply for testing this.

---

commit 658488b7577b7b2242372c43f081f55e2d274615
Author: Michael S. Tsirkin <mst@...lanox.co.il>
Date:   Mon Oct 30 01:28:40 2006 +0200

    Revert "[PATCH] blockdev.c: check driver layer errors"
    
    This reverts commit 4d7dd8fd9557840162b724a8ac1366dd78a12dff.

diff --git a/fs/block_dev.c b/fs/block_dev.c
index bc8f27c..b15ad29 100644
--- a/fs/block_dev.c
+++ b/fs/block_dev.c
@@ -545,11 +545,11 @@ static struct kobject *bdev_get_holder(s
 		return kobject_get(bdev->bd_disk->holder_dir);
 }
 
-static int add_symlink(struct kobject *from, struct kobject *to)
+static void add_symlink(struct kobject *from, struct kobject *to)
 {
 	if (!from || !to)
-		return 0;
-	return sysfs_create_link(from, to, kobject_name(to));
+		return;
+	sysfs_create_link(from, to, kobject_name(to));
 }
 
 static void del_symlink(struct kobject *from, struct kobject *to)
@@ -650,38 +650,30 @@ static void free_bd_holder(struct bd_hol
  * If there is no matching entry with @bo in @bdev->bd_holder_list,
  * add @bo to the list, create symlinks.
  *
- * Returns 0 if symlinks are created or already there.
- * Returns -ve if something fails and @bo can be freed.
+ * Returns 1 if @bo was added to the list.
+ * Returns 0 if @bo wasn't used by any reason and should be freed.
  */
 static int add_bd_holder(struct block_device *bdev, struct bd_holder *bo)
 {
 	struct bd_holder *tmp;
-	int ret;
 
 	if (!bo)
-		return -EINVAL;
+		return 0;
 
 	list_for_each_entry(tmp, &bdev->bd_holder_list, list) {
 		if (tmp->sdir == bo->sdir) {
 			tmp->count++;
-			/* We've already done what we need to do here. */
-			free_bd_holder(bo);
 			return 0;
 		}
 	}
 
 	if (!bd_holder_grab_dirs(bdev, bo))
-		return -EBUSY;
+		return 0;
 
-	ret = add_symlink(bo->sdir, bo->sdev);
-	if (ret == 0) {
-		ret = add_symlink(bo->hdir, bo->hdev);
-		if (ret)
-			del_symlink(bo->sdir, bo->sdev);
-	}
-	if (ret == 0)
-		list_add_tail(&bo->list, &bdev->bd_holder_list);
-	return ret;
+	add_symlink(bo->sdir, bo->sdev);
+	add_symlink(bo->hdir, bo->hdev);
+	list_add_tail(&bo->list, &bdev->bd_holder_list);
+	return 1;
 }
 
 /**
@@ -751,9 +743,7 @@ static int bd_claim_by_kobject(struct bl
 
 	mutex_lock_nested(&bdev->bd_mutex, BD_MUTEX_PARTITION);
 	res = bd_claim(bdev, holder);
-	if (res == 0)
-		res = add_bd_holder(bdev, bo);
-	if (res)
+	if (res || !add_bd_holder(bdev, bo))
 		free_bd_holder(bo);
 	mutex_unlock(&bdev->bd_mutex);
 


-- 
MST
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