From: Ingo Molnar <mingo@elte.hu>
Date: Tue, 16 Jun 2009 14:11:14 +0000 (+0200)
Subject: dma-debug: Put all hash-chain locks into the same lock class
X-Git-Url: http://drtracing.org/?a=commitdiff_plain;h=b0a5b83ee0fce9dbf8ff5fe1f8c9ae7dfafe458c;p=deliverable%2Flinux.git

dma-debug: Put all hash-chain locks into the same lock class

Alan Cox reported that lockdep runs out of its stack-trace entries
with certain configs:

 BUG: MAX_STACK_TRACE_ENTRIES too low

This happens because there are 1024 hash buckets, each with a
separate lock. Lockdep puts each lock into a separate lock class and
tracks them independently.

But in reality we never take more than one of the buckets, so they
really belong into a single lock-class. Annotate the has bucket lock
init accordingly.

[ Impact: reduce the lockdep footprint of dma-debug ]

Reported-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>
---

diff --git a/lib/dma-debug.c b/lib/dma-debug.c
index a9b6b5c9e091..c9187fed0b93 100644
--- a/lib/dma-debug.c
+++ b/lib/dma-debug.c
@@ -716,7 +716,7 @@ void dma_debug_init(u32 num_entries)
 
 	for (i = 0; i < HASH_SIZE; ++i) {
 		INIT_LIST_HEAD(&dma_entry_hash[i].list);
-		dma_entry_hash[i].lock = SPIN_LOCK_UNLOCKED;
+		spin_lock_init(&dma_entry_hash[i].lock);
 	}
 
 	if (dma_debug_fs_init() != 0) {