From 94744ac0cd723f01ca21c98ff21fedb79eef3c61 Mon Sep 17 00:00:00 2001 From: Roland Dreier Date: Mon, 18 Sep 2006 19:28:17 +0200 Subject: [PATCH] Convert idr's internal locking to _irqsave variant 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. Signed-off-by: Roland Dreier Signed-off-by: Adrian Bunk --- lib/idr.c | 16 ++++++++++------ 1 file changed, 10 insertions(+), 6 deletions(-) diff --git a/lib/idr.c b/lib/idr.c index de19030a999b..595c76bcb8dd 100644 --- a/lib/idr.c +++ b/lib/idr.c @@ -37,14 +37,15 @@ static kmem_cache_t *idr_layer_cache; static struct idr_layer *alloc_layer(struct idr *idp) { struct idr_layer *p; + unsigned long flags; - spin_lock(&idp->lock); + spin_lock_irqsave(&idp->lock, flags); if ((p = idp->id_free)) { idp->id_free = p->ary[0]; idp->id_free_cnt--; p->ary[0] = NULL; } - spin_unlock(&idp->lock); + spin_unlock_irqrestore(&idp->lock, flags); return(p); } @@ -58,12 +59,14 @@ static void __free_layer(struct idr *idp, struct idr_layer *p) static void free_layer(struct idr *idp, struct idr_layer *p) { + unsigned long flags; + /* * Depends on the return element being zeroed. */ - spin_lock(&idp->lock); + spin_lock_irqsave(&idp->lock, flags); __free_layer(idp, p); - spin_unlock(&idp->lock); + spin_unlock_irqrestore(&idp->lock, flags); } /** @@ -167,6 +170,7 @@ static int idr_get_new_above_int(struct idr *idp, void *ptr, int starting_id) { struct idr_layer *p, *new; int layers, v, id; + unsigned long flags; id = starting_id; build_up: @@ -190,14 +194,14 @@ build_up: * The allocation failed. If we built part of * the structure tear it down. */ - spin_lock(&idp->lock); + spin_lock_irqsave(&idp->lock, flags); for (new = p; p && p != idp->top; new = p) { p = p->ary[0]; new->ary[0] = NULL; new->bitmap = new->count = 0; __free_layer(idp, new); } - spin_unlock(&idp->lock); + spin_unlock_irqrestore(&idp->lock, flags); return -1; } new->ary[0] = p; -- 2.39.5