Commit 84bc227d7fde049a568cd58a5610613feedc0dff
Committed by
Linus Torvalds
Linus Torvalds
1 parent
43506fad21
Exists in
master
and in
4 other branches
mm/dmapool.c: take lock only once in dma_pool_free()
dma_pool_free() scans for the page to free in the pool list holding the pool lock. Then it releases the lock basically to acquire it immediately again. Modify the code to only take the lock once. This will do some additional loops and computations with the lock held in if memory debugging is activated. If it is not activated the only new operations with this lock is one if and one substraction. Signed-off-by: Rolf Eike Beer <eike-kernel@sf-tec.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Showing 1 changed file with 6 additions and 8 deletions Side-by-side Diff
mm/dmapool.c
| ... | ... | @@ -355,20 +355,15 @@ |
| 355 | 355 | |
| 356 | 356 | static struct dma_page *pool_find_page(struct dma_pool *pool, dma_addr_t dma) |
| 357 | 357 | { |
| 358 | - unsigned long flags; | |
| 359 | 358 | struct dma_page *page; |
| 360 | 359 | |
| 361 | - spin_lock_irqsave(&pool->lock, flags); | |
| 362 | 360 | list_for_each_entry(page, &pool->page_list, page_list) { |
| 363 | 361 | if (dma < page->dma) |
| 364 | 362 | continue; |
| 365 | 363 | if (dma < (page->dma + pool->allocation)) |
| 366 | - goto done; | |
| 364 | + return page; | |
| 367 | 365 | } |
| 368 | - page = NULL; | |
| 369 | - done: | |
| 370 | - spin_unlock_irqrestore(&pool->lock, flags); | |
| 371 | - return page; | |
| 366 | + return NULL; | |
| 372 | 367 | } |
| 373 | 368 | |
| 374 | 369 | /** |
| 375 | 370 | |
| ... | ... | @@ -386,8 +381,10 @@ |
| 386 | 381 | unsigned long flags; |
| 387 | 382 | unsigned int offset; |
| 388 | 383 | |
| 384 | + spin_lock_irqsave(&pool->lock, flags); | |
| 389 | 385 | page = pool_find_page(pool, dma); |
| 390 | 386 | if (!page) { |
| 387 | + spin_unlock_irqrestore(&pool->lock, flags); | |
| 391 | 388 | if (pool->dev) |
| 392 | 389 | dev_err(pool->dev, |
| 393 | 390 | "dma_pool_free %s, %p/%lx (bad dma)\n", |
| ... | ... | @@ -401,6 +398,7 @@ |
| 401 | 398 | offset = vaddr - page->vaddr; |
| 402 | 399 | #ifdef DMAPOOL_DEBUG |
| 403 | 400 | if ((dma - page->dma) != offset) { |
| 401 | + spin_unlock_irqrestore(&pool->lock, flags); | |
| 404 | 402 | if (pool->dev) |
| 405 | 403 | dev_err(pool->dev, |
| 406 | 404 | "dma_pool_free %s, %p (bad vaddr)/%Lx\n", |
| ... | ... | @@ -418,6 +416,7 @@ |
| 418 | 416 | chain = *(int *)(page->vaddr + chain); |
| 419 | 417 | continue; |
| 420 | 418 | } |
| 419 | + spin_unlock_irqrestore(&pool->lock, flags); | |
| 421 | 420 | if (pool->dev) |
| 422 | 421 | dev_err(pool->dev, "dma_pool_free %s, dma %Lx " |
| 423 | 422 | "already free\n", pool->name, |
| ... | ... | @@ -432,7 +431,6 @@ |
| 432 | 431 | memset(vaddr, POOL_POISON_FREED, pool->size); |
| 433 | 432 | #endif |
| 434 | 433 | |
| 435 | - spin_lock_irqsave(&pool->lock, flags); | |
| 436 | 434 | page->in_use--; |
| 437 | 435 | *(int *)vaddr = page->offset; |
| 438 | 436 | page->offset = offset; |