On Wed, Mar 21, 2012 at 11:32:14PM -0700, Dan Williams wrote:
> In scsi at least two cases of the parent device being deleted before the
> child is added have been observed.
>
> 1/ scsi is performing async scans and the device is removed prior to the
> async can thread running.
>
> 2/ libsas discovery event running after the parent port has been torn
> down.
>
> Result in crash signatures like:
> BUG: unable to handle kernel NULL pointer dereference at 0000000000000098
> IP: [<ffffffff8115e100>] sysfs_create_dir+0x32/0xb6
> ...
> Process scsi_scan_8 (pid: 5417, threadinfo ffff88080bd16000, task ffff880801b8a0b0)
> Stack:
> 00000000fffffffe ffff880813470628 ffff88080bd17cd0 ffff88080614b7e8
> ffff88080b45c108 00000000fffffffe ffff88080bd17d20 ffffffff8125e4a8
> ffff88080bd17cf0 ffffffff81075149 ffff88080bd17d30 ffff88080614b7e8
> Call Trace:
> [<ffffffff8125e4a8>] kobject_add_internal+0x120/0x1e3
> [<ffffffff81075149>] ? trace_hardirqs_on+0xd/0xf
> [<ffffffff8125e641>] kobject_add_varg+0x41/0x50
> [<ffffffff8125e70b>] kobject_add+0x64/0x66
> [<ffffffff8131122b>] device_add+0x12d/0x63a
>
> These scenarios need to be cleaned up, but in the meantime the system
> need not crash if this ordering occurs. Instead report:
>
> kobject_add_internal failed for target8:0:16 (error: -2 parent: end_device-8:0:24)
> Pid: 2942, comm: scsi_scan_8 Not tainted 3.3.0-rc7-isci+ #2
> Call Trace:
> [<ffffffff8125e551>] kobject_add_internal+0x1c1/0x1f3
> [<ffffffff81075149>] ? trace_hardirqs_on+0xd/0xf
> [<ffffffff8125e659>] kobject_add_varg+0x41/0x50
> [<ffffffff8125e723>] kobject_add+0x64/0x66
> [<ffffffff8131124b>] device_add+0x12d/0x63a
> [<ffffffff8125e0ef>] ? kobject_put+0x4c/0x50
> [<ffffffff8132f370>] scsi_sysfs_add_sdev+0x4e/0x28a
> [<ffffffff8132dce3>] do_scan_async+0x9c/0x145
>
> Cc: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
> Signed-off-by: Dan Williams <dan.j.williams@xxxxxxxxx>
> ---
> fs/sysfs/dir.c | 3 +++
> lib/kobject.c | 7 ++++---
> 2 files changed, 7 insertions(+), 3 deletions(-)
>
> diff --git a/fs/sysfs/dir.c b/fs/sysfs/dir.c
> index 7fdf6a7..86521ee 100644
> --- a/fs/sysfs/dir.c
> +++ b/fs/sysfs/dir.c
> @@ -714,6 +714,9 @@ int sysfs_create_dir(struct kobject * kobj)
> else
> parent_sd = &sysfs_root;
>
> + if (!parent_sd)
> + return -ENOENT;
> +
> if (sysfs_ns_type(parent_sd))
> ns = kobj->ktype->namespace(kobj);
> type = sysfs_read_ns_type(kobj);
So what happens if this is true? Does this patch fix the oops? What
kernels should this be applied to where this problem has been seen?
> diff --git a/lib/kobject.c b/lib/kobject.c
> index c33d7a1..e5f86c0 100644
> --- a/lib/kobject.c
> +++ b/lib/kobject.c
> @@ -192,13 +192,14 @@ static int kobject_add_internal(struct kobject *kobj)
>
> /* be noisy on error issues */
> if (error == -EEXIST)
> - printk(KERN_ERR "%s failed for %s with "
> + pr_err("%s failed for %s with "
> "-EEXIST, don't try to register things with "
> "the same name in the same directory.\n",
> __func__, kobject_name(kobj));
> else
> - printk(KERN_ERR "%s failed for %s (%d)\n",
> - __func__, kobject_name(kobj), error);
> + pr_err("%s failed for %s (error: %d parent: %s)\n",
> + __func__, kobject_name(kobj), error,
> + parent ? kobject_name(parent) : "'none'");
> dump_stack();
> } else
> kobj->state_in_sysfs = 1;
These changes have nothing to do with the above fix, so why include them
here?
And note, I hate pr_err(), what's wrong with printk() in this instance?
greg k-h
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