From: Roland Dreier Date: Thu, 31 Aug 2006 23:43:06 +0000 (-0700) Subject: IB/mthca: Use IRQ safe locks to protect allocation bitmaps X-Git-Tag: v2.6.18-rc6~27^2 X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=5a4e6dccbc0cd1b726820b782daebf887dcb95e9;p=linux-2.6 IB/mthca: Use IRQ safe locks to protect allocation bitmaps It is supposed to be OK to call mthca_create_ah() and mthca_destroy_ah() from any context. However, for mem-full HCAs, these functions use the mthca_alloc() and mthca_free() bitmap helpers, and those helpers use non-IRQ-safe spin_lock() internally. Lockdep correctly warns that this could lead to a deadlock. Fix this by changing mthca_alloc() and mthca_free() to use spin_lock_irqsave(). Signed-off-by: Roland Dreier --- diff --git a/drivers/infiniband/hw/mthca/mthca_allocator.c b/drivers/infiniband/hw/mthca/mthca_allocator.c index 25157f57a6..f930e55b58 100644 --- a/drivers/infiniband/hw/mthca/mthca_allocator.c +++ b/drivers/infiniband/hw/mthca/mthca_allocator.c @@ -41,9 +41,11 @@ /* Trivial bitmap-based allocator */ u32 mthca_alloc(struct mthca_alloc *alloc) { + unsigned long flags; u32 obj; - spin_lock(&alloc->lock); + spin_lock_irqsave(&alloc->lock, flags); + obj = find_next_zero_bit(alloc->table, alloc->max, alloc->last); if (obj >= alloc->max) { alloc->top = (alloc->top + alloc->max) & alloc->mask; @@ -56,19 +58,24 @@ u32 mthca_alloc(struct mthca_alloc *alloc) } else obj = -1; - spin_unlock(&alloc->lock); + spin_unlock_irqrestore(&alloc->lock, flags); return obj; } void mthca_free(struct mthca_alloc *alloc, u32 obj) { + unsigned long flags; + obj &= alloc->max - 1; - spin_lock(&alloc->lock); + + spin_lock_irqsave(&alloc->lock, flags); + clear_bit(obj, alloc->table); alloc->last = min(alloc->last, obj); alloc->top = (alloc->top + alloc->max) & alloc->mask; - spin_unlock(&alloc->lock); + + spin_unlock_irqrestore(&alloc->lock, flags); } int mthca_alloc_init(struct mthca_alloc *alloc, u32 num, u32 mask,