From: "jkenisto at us dot ibm dot com" <sourceware-bugzilla@sourceware.org>
To: systemtap@sources.redhat.com
Subject: [Bug kprobes/3541] unsafe printk calls in hand-coded kprobe handlers
Date: Wed, 22 Nov 2006 00:43:00 -0000 [thread overview]
Message-ID: <20061122000532.31988.qmail@sourceware.org> (raw)
In-Reply-To: <20061117231901.3541.jkenisto@us.ibm.com>
------- Additional Comments From jkenisto at us dot ibm dot com 2006-11-22 00:05 -------
Since kprobes doesn't allow handlers to re-enter, the likely deadlock scenario
is anybody -> printk -> release_console_sem [locks logbuf_lock] -> up -> ... ->
try_to_wake_up -> activate_task -> handler -> printk [goes for logbuf_lock again].
Re: (2b), spin_trylock_irqsave() (which is what we want) can fail in perfectly
benign scenarios. If it does, it's a deadlock only if printk_cpu ==
smp_processor_id(). Otherwise, just go for the lock again with spinlock_irq_save().
--
http://sourceware.org/bugzilla/show_bug.cgi?id=3541
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next prev parent reply other threads:[~2006-11-22 0:05 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-11-18 14:27 [Bug kprobes/3541] New: " jkenisto at us dot ibm dot com
2006-11-22 0:43 ` jkenisto at us dot ibm dot com [this message]
2009-04-01 17:36 ` [Bug kprobes/3541] " fche at redhat dot com
2009-10-07 14:59 ` fche at redhat dot com
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