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); 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; -- To unsubscribe from this list: send the line "unsubscribe linux-ide" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html