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Date: Wed, 18 May 2011 14:27:17 +0900 From: Tetsuo Handa <penguin-kernel@...ove.SAKURA.ne.jp> To: john.stultz@...aro.org Cc: tytso@....edu, mina86@...a86.com, jirislaby@...il.com, kosaki.motohiro@...fujitsu.com, rientjes@...gle.com, dave@...ux.vnet.ibm.com, linux-kernel@...r.kernel.org Subject: Re: [PATCH 0/3] v4 Improve task->comm locking situation John Stultz wrote: > So I think this approach is definitely worth trying. However, I think > converting to RCU will be much easier once we've first converted all > current comm users to making use of the get_task_comm accessor > functions. In this way my hope is my current proposal will serve as a > cleanup step before further optimizations can be done. OK. But I guess converting all current comm users to making use of the get_task_comm accessor is not easy because using get_task_comm() changes locking dependency. I think replacing "%s", tsk->comm with "%ptc", tsk (without using get_task_comm() inside pointer() because introducing a new lock might cause problem since callers can be inside a delicate condition based on the assumption that vsnprintf() will not block) should come first in order to minimize direct ->comm users who may not be ready for this change. After that, trying to replace task->comm with char buf[TASK_COMM_LEN]; get_task_comm(task, buf) (with cautions for already held locks) may be considered. By the way, sprintf(current->comm, "drbd%d_receiver", minor); in drivers/block/drbd/drbd_receiver.c may be off-by-one because DRBD_MINOR_COUNT_MAX is 256. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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