[openib-general] [PATCH] Convert idr's internal locking to _irqsave variant

[Ingo Molnar]

* Roland Dreier <rdreier at cisco.com> wrote:

> Currently, the code in lib/idr.c uses a bare spin_lock(&idp->lock) to 
> do internal locking.  This is a nasty trap for code that might call 
> idr functions from different contexts; for example, it seems perfectly 
> reasonable to call idr_get_new() from process context and idr_remove() 
> from interrupt context -- but with the current locking this would lead 
> to a potential deadlock.
> 
> The simplest fix for this is to just convert the idr locking to use 
> spin_lock_irqsave().
> 
> In particular, this fixes a very complicated locking issue detected by 
> lockdep, involving the ib_ipoib driver's priv->lock and 
> dev->_xmit_lock, which get involved with the ib_sa module's 
> query_idr.lock.
> 
> Cc: Arjan van de Ven <arjan at infradead.org>
> Cc: Ingo Molnar <mingo at elte.hu>

Acked-by: Ingo Molnar <mingo at elte.hu>

	Ingo