Commit 4a9949d7 authored by Andy Wingo's avatar Andy Wingo Committed by Linus Torvalds

[PATCH] raw1394: fix locking in the presence of SMP and interrupts

Changes all spinlocks that can be held during an irq handler to disable
interrupts while the lock is held.  Changes spin_[un]lock_irq to use the
irqsave/irqrestore variants for robustness and readability.

In raw1394.c:handle_iso_listen(), don't grab host_info_lock at all -- we're
not accessing host_info_list or host_count, and holding this lock while
trying to tasklet_kill the iso tasklet this can cause an ABBA deadlock if
ohci:dma_rcv_tasklet is running and tries to grab host_info_lock in
raw1394.c:receive_iso.  Test program attached reliably deadlocks all SMP
machines I have been able to test without this patch.
Signed-off-by: default avatarAndy Wingo <wingo@pobox.com>
Acked-by: default avatarBen Collins <bcollins@ubuntu.com>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent c367c21c
...@@ -2283,8 +2283,9 @@ static void ohci_schedule_iso_tasklets(struct ti_ohci *ohci, ...@@ -2283,8 +2283,9 @@ static void ohci_schedule_iso_tasklets(struct ti_ohci *ohci,
{ {
struct ohci1394_iso_tasklet *t; struct ohci1394_iso_tasklet *t;
unsigned long mask; unsigned long mask;
unsigned long flags;
spin_lock(&ohci->iso_tasklet_list_lock); spin_lock_irqsave(&ohci->iso_tasklet_list_lock, flags);
list_for_each_entry(t, &ohci->iso_tasklet_list, link) { list_for_each_entry(t, &ohci->iso_tasklet_list, link) {
mask = 1 << t->context; mask = 1 << t->context;
...@@ -2295,8 +2296,7 @@ static void ohci_schedule_iso_tasklets(struct ti_ohci *ohci, ...@@ -2295,8 +2296,7 @@ static void ohci_schedule_iso_tasklets(struct ti_ohci *ohci,
tasklet_schedule(&t->tasklet); tasklet_schedule(&t->tasklet);
} }
spin_unlock(&ohci->iso_tasklet_list_lock); spin_unlock_irqrestore(&ohci->iso_tasklet_list_lock, flags);
} }
static irqreturn_t ohci_irq_handler(int irq, void *dev_id, static irqreturn_t ohci_irq_handler(int irq, void *dev_id,
......
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