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Date: Sat, 03 Sep 2005 08:20:01 -0600 (MDT)
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To: sebastien.bourdeauducq@gmail.com
From: "M. Warner Losh" <imp@bsdimp.com>
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Cc: freebsd-usb@freebsd.org
Subject: Re: Mutexes in USB callbacks ?
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In message: <20050903.081802.78021370.imp@bsdimp.com>
            M. Warner Losh <imp@bsdimp.com> writes:
: In message: <200509031614.51362.sebastien.bourdeauducq@gmail.com>
:             Sebastien <sebastien.bourdeauducq@gmail.com> writes:
: : Hello,
: : Is it finally possible or not to acquire a mutex in an USB callback function, 
: : under FreeBSD 5-STABLE ?
: : I have controversial information about this :(
: 
: Since the callback functions are called from an interrupt handler
: which is an ithread protected by Giant, there should be no problems
: doing this.

However, since it is an ithread, and usb is a commonly shared device,
any sleeping you do there will delay other device's interrupt hanlders
from running.

Warner