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Message-ID: <20130112174607.GB22338@redhat.com> Date: Sat, 12 Jan 2013 18:46:07 +0100 From: Oleg Nesterov <oleg@...hat.com> To: Michel Lespinasse <walken@...gle.com> Cc: Thomas Gleixner <tglx@...utronix.de>, David Howells <dhowells@...hat.com>, Salman Qazi <sqazi@...gle.com>, LKML <linux-kernel@...r.kernel.org> Subject: Re: [PATCH] rwlock_t unfairness and tasklist_lock On 01/11, Michel Lespinasse wrote: > > So I looked again at getpriority() since that's what I had used for my > DOS test code, and it looks like everything there is already protected > by RCU or smaller granularity locks and refcounts. Patch attached to > remove this tasklist_lock usage. And probably the change in getpriority() is fine, but ... > @@ -189,7 +189,6 @@ SYSCALL_DEFINE3(setpriority, int, which, int, who, int, niceval) > niceval = 19; > > rcu_read_lock(); > - read_lock(&tasklist_lock); > switch (which) { > case PRIO_PROCESS: > if (who) > @@ -226,7 +225,6 @@ SYSCALL_DEFINE3(setpriority, int, which, int, who, int, niceval) > break; > } > out_unlock: > - read_unlock(&tasklist_lock); you also changed setpriority(), this should be documented at least ;) OK. Even without this change, say, sys_setpriority(PRIO_PGRP) can obviously race with fork(), so this change probably is not bad. Oleg. -- 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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