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From: Johannes Berg <johannes@sipsolutions.net>
To: Nicolai Stange <nicstange@gmail.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	"Paul E.McKenney" <paulmck@linux.vnet.ibm.com>,
	linux-kernel@vger.kernel.org
Subject: Re: [RFC PATCH 8/9] debugfs: defer debugfs_fsdata allocation to first usage
Date: Wed, 03 May 2017 07:43:58 +0200	[thread overview]
Message-ID: <1493790238.2602.3.camel@sipsolutions.net> (raw)
In-Reply-To: <87y3ufvxaz.fsf@gmail.com> (sfid-20170502_220600_227096_F45CC85C)

On Tue, 2017-05-02 at 22:05 +0200, Nicolai Stange wrote:

> > So either you could return some valid ops (perhaps
> > debugfs_noop_file_operations although those don't have .name or
> > .poll, so it doesn't cover everything), or you can just BUG_ON()
> > here directly, saving the incomprehensible crash later.
> 
> The purpose of that WARN_ON() there was to turn a potentially
> incomprehensible crash into a comprehensible one ;)
> 
> In order to avoid a new BUG_ON(), what about keeping the WARN_ON() as
> is and returning NULL instead of the garbage? That would crash
> current on first access and the earlier warning would hopefully give
> some clue?

Yeah, I guess that might work. Probably less harmful to the system than
a BUG_ON(), but I still operate under the assumption that there might
actually be something mapped at NULL - not sure if that's still true.

johannes

  reply	other threads:[~2017-05-03  5:44 UTC|newest]

Thread overview: 46+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-03-23 14:54 deadlock in synchronize_srcu() in debugfs? Johannes Berg
2017-03-23 15:29 ` Johannes Berg
2017-03-24  8:56   ` Johannes Berg
2017-03-24  9:24     ` Johannes Berg
2017-03-24 17:45       ` Paul E. McKenney
2017-03-24 18:51         ` Johannes Berg
2017-03-24 19:33           ` Paul E. McKenney
2017-03-24 20:20             ` Paul E. McKenney
2017-03-27 11:18               ` Johannes Berg
2017-03-23 15:36 ` Nicolai Stange
2017-03-23 15:47   ` Johannes Berg
2017-03-27 11:36   ` Johannes Berg
2017-03-30  7:32     ` Nicolai Stange
2017-03-30  7:55       ` Johannes Berg
2017-03-30 10:27         ` Nicolai Stange
2017-03-30 11:11           ` Johannes Berg
2017-03-31  9:03             ` Nicolai Stange
2017-03-31  9:44               ` Johannes Berg
2017-04-16  9:51               ` [RFC PATCH 0/9] debugfs: per-file removal protection Nicolai Stange
2017-04-16  9:51                 ` [RFC PATCH 1/9] debugfs: add support for more elaborate ->d_fsdata Nicolai Stange
2017-04-16  9:51                 ` [RFC PATCH 2/9] debugfs: implement per-file removal protection Nicolai Stange
2017-04-18  2:23                   ` [lkp-robot] [debugfs] f3e7155d08: BUG:unable_to_handle_kernel kernel test robot
2017-04-18  2:23                     ` kernel test robot
2017-04-23 18:37                     ` Nicolai Stange
2017-04-23 18:37                       ` Nicolai Stange
2017-04-24  6:36                       ` Ye Xiaolong
2017-04-24  6:36                         ` Ye Xiaolong
2017-04-16  9:51                 ` [RFC PATCH 3/9] debugfs: debugfs_real_fops(): drop __must_hold sparse annotation Nicolai Stange
2017-04-16  9:51                 ` [RFC PATCH 4/9] debugfs: convert to debugfs_file_get() and -put() Nicolai Stange
2017-04-16  9:51                 ` [RFC PATCH 5/9] IB/hfi1: " Nicolai Stange
2017-04-16  9:51                 ` [RFC PATCH 6/9] debugfs: purge obsolete SRCU based removal protection Nicolai Stange
2017-04-16  9:51                 ` [RFC PATCH 7/9] debugfs: call debugfs_real_fops() only after debugfs_file_get() Nicolai Stange
2017-04-16  9:51                 ` [RFC PATCH 8/9] debugfs: defer debugfs_fsdata allocation to first usage Nicolai Stange
2017-04-18  9:36                   ` Johannes Berg
2017-05-02 20:05                     ` Nicolai Stange
2017-05-03  5:43                       ` Johannes Berg [this message]
2017-04-16  9:51                 ` [RFC PATCH 9/9] debugfs: free debugfs_fsdata instances Nicolai Stange
2017-04-17 16:01                   ` Paul E. McKenney
2017-04-18  9:39                     ` Johannes Berg
2017-04-18 13:31                       ` Paul E. McKenney
2017-04-18 13:40                         ` Johannes Berg
2017-04-18 15:17                           ` Paul E. McKenney
2017-04-18 15:20                             ` Johannes Berg
2017-04-18 17:19                               ` Paul E. McKenney
2017-03-23 15:37 ` deadlock in synchronize_srcu() in debugfs? Paul E. McKenney
2017-03-23 15:46   ` Johannes Berg

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