From 577a31b661349769ba54378cb2979a9d3ecad4ed Mon Sep 17 00:00:00 2001 From: Andrew Warfield Date: Thu, 28 Sep 2006 12:03:01 -0700 Subject: [PATCH] [BLKTAP] Fix SMP debugging assert failures in blktap blktap is calling non-atomic kernel functions with irqs disabled, which hits various kernel debug traps if those are enabled. The problem is req_increase(), which takes the pending_free_lock. This function is currently only ever called from module initialiation, where it is impossible for it to race against anything else. Its companion, req_decrease(), is not called at all. Fix by removing the offending locking from req_increase() and, while we're at it, remove req_decrease() entirely. Signed-off-by: Stephen Tweedie --- .../drivers/xen/blktap/blktap.c | 37 +------------------ 1 file changed, 1 insertion(+), 36 deletions(-) diff --git a/linux-2.6-xen-sparse/drivers/xen/blktap/blktap.c b/linux-2.6-xen-sparse/drivers/xen/blktap/blktap.c index c3ba5ac7f1..a5b9e56c1a 100644 --- a/linux-2.6-xen-sparse/drivers/xen/blktap/blktap.c +++ b/linux-2.6-xen-sparse/drivers/xen/blktap/blktap.c @@ -694,11 +694,8 @@ static int req_increase(void) { int i, j; struct page *page; - unsigned long flags; int ret; - spin_lock_irqsave(&pending_free_lock, flags); - ret = -EINVAL; if (mmap_alloc >= MAX_PENDING_REQS || mmap_lock) goto done; @@ -763,8 +760,7 @@ static int req_increase(void) mmap_alloc++; DPRINTK("# MMAPs increased to %d\n",mmap_alloc); - done: - spin_unlock_irqrestore(&pending_free_lock, flags); +done: return ret; } @@ -794,37 +790,6 @@ static void mmap_req_del(int mmap) mmap_alloc--; } -/*N.B. Currently unused - will be accessed via sysfs*/ -static void req_decrease(void) -{ - pending_req_t *req; - int i; - unsigned long flags; - - spin_lock_irqsave(&pending_free_lock, flags); - - DPRINTK("Req decrease called.\n"); - if (mmap_lock || mmap_alloc == 1) - goto done; - - mmap_lock = 1; - mmap_inuse = MAX_PENDING_REQS; - - /*Go through reqs and remove any that aren't in use*/ - for (i = 0; i < MAX_PENDING_REQS ; i++) { - req = &pending_reqs[mmap_alloc-1][i]; - if (req->inuse == 0) { - list_del(&req->free_list); - mmap_inuse--; - } - } - if (mmap_inuse == 0) - mmap_req_del(mmap_alloc-1); - done: - spin_unlock_irqrestore(&pending_free_lock, flags); - return; -} - static pending_req_t* alloc_req(void) { pending_req_t *req = NULL; -- 2.30.2