[RFC PATCH v2 2/5] dma-pool: allow user to disable atomic pool
From: Baoquan He <hidden>
Date: 2021-08-10 09:50:09
Also in:
lkml
Subsystem:
dma mapping helpers, documentation, the rest · Maintainers:
Marek Szyprowski, Jonathan Corbet, Linus Torvalds
In the current code, three atomic memory pools are always created, atomic_pool_kernel|dma|dma32, even though 'coherent_pool=0' is specified in kernel command line. In fact, atomic pool is only necessary when CONFIG_DMA_DIRECT_REMAP=y or mem_encrypt_active=y which are needed on few ARCHes. So change code to allow user to disable atomic pool by specifying 'coherent_pool=0'. Meanwhile, update the relevant document in kernel-parameter.txt. Signed-off-by: Baoquan He <redacted> --- Documentation/admin-guide/kernel-parameters.txt | 3 ++- kernel/dma/pool.c | 7 +++++-- 2 files changed, 7 insertions(+), 3 deletions(-)
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index 970ed65db89f..620d38b5ce2d 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt@@ -653,7 +653,8 @@ coherent_pool=nn[KMG] [ARM,KNL] Sets the size of memory pool for coherent, atomic dma - allocations. Otherwise the default size will be scaled + allocations. A value of 0 disables the three atomic + memory pool. Otherwise the default size will be scaled with memory capacity, while clamped between 128K and 1 << (PAGE_SHIFT + MAX_ORDER-1).
diff --git a/kernel/dma/pool.c b/kernel/dma/pool.c
index 5f84e6cdb78e..5a85804b5beb 100644
--- a/kernel/dma/pool.c
+++ b/kernel/dma/pool.c@@ -21,7 +21,7 @@ static struct gen_pool *atomic_pool_kernel __ro_after_init; static unsigned long pool_size_kernel; /* Size can be defined by the coherent_pool command line */ -static size_t atomic_pool_size; +static unsigned long atomic_pool_size = -1; /* Dynamic background expansion when the atomic pool is near capacity */ static struct work_struct atomic_pool_work;
@@ -188,11 +188,14 @@ static int __init dma_atomic_pool_init(void) { int ret = 0; + if (!atomic_pool_size) + return 0; + /* * If coherent_pool was not used on the command line, default the pool * sizes to 128KB per 1GB of memory, min 128KB, max MAX_ORDER-1. */ - if (!atomic_pool_size) { + if (atomic_pool_size == -1) { unsigned long pages = totalram_pages() / (SZ_1G / SZ_128K); pages = min_t(unsigned long, pages, MAX_ORDER_NR_PAGES); atomic_pool_size = max_t(size_t, pages << PAGE_SHIFT, SZ_128K);
--
2.17.2