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| author | Jakub Kicinski <kuba@kernel.org> | 2020-07-09 17:42:44 -0700 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2020-07-10 13:54:00 -0700 |
| commit | a2b992c828f7651db369ba8f0eb0818d70232636 (patch) | |
| tree | f66e1c6eeb40d7acf38ad802e80df4efdde2e2f3 /mm | |
| parent | 8fb49c0109f47e4a25e8ba36abd8381afbfa7a08 (diff) | |
| download | lwn-a2b992c828f7651db369ba8f0eb0818d70232636.tar.gz lwn-a2b992c828f7651db369ba8f0eb0818d70232636.zip | |
debugfs: make sure we can remove u32_array files cleanly
debugfs_create_u32_array() allocates a small structure to wrap
the data and size information about the array. If users ever
try to remove the file this leads to a leak since nothing ever
frees this wrapper.
That said there are no upstream users of debugfs_create_u32_array()
that'd remove a u32 array file (we only have one u32 array user in
CMA), so there is no real bug here.
Make callers pass a wrapper they allocated. This way the lifetime
management of the wrapper is on the caller, and we can avoid the
potential leak in debugfs.
CC: Chucheng Luo <luochucheng@vivo.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'mm')
| -rw-r--r-- | mm/cma.h | 3 | ||||
| -rw-r--r-- | mm/cma_debug.c | 7 |
2 files changed, 7 insertions, 3 deletions
@@ -2,6 +2,8 @@ #ifndef __MM_CMA_H__ #define __MM_CMA_H__ +#include <linux/debugfs.h> + struct cma { unsigned long base_pfn; unsigned long count; @@ -11,6 +13,7 @@ struct cma { #ifdef CONFIG_CMA_DEBUGFS struct hlist_head mem_head; spinlock_t mem_head_lock; + struct debugfs_u32_array dfs_bitmap; #endif const char *name; }; diff --git a/mm/cma_debug.c b/mm/cma_debug.c index 4e6cbe2f586e..d5bf8aa34fdc 100644 --- a/mm/cma_debug.c +++ b/mm/cma_debug.c @@ -164,7 +164,6 @@ static void cma_debugfs_add_one(struct cma *cma, struct dentry *root_dentry) { struct dentry *tmp; char name[16]; - int u32s; scnprintf(name, sizeof(name), "cma-%s", cma->name); @@ -180,8 +179,10 @@ static void cma_debugfs_add_one(struct cma *cma, struct dentry *root_dentry) debugfs_create_file("used", 0444, tmp, cma, &cma_used_fops); debugfs_create_file("maxchunk", 0444, tmp, cma, &cma_maxchunk_fops); - u32s = DIV_ROUND_UP(cma_bitmap_maxno(cma), BITS_PER_BYTE * sizeof(u32)); - debugfs_create_u32_array("bitmap", 0444, tmp, (u32 *)cma->bitmap, u32s); + cma->dfs_bitmap.array = (u32 *)cma->bitmap; + cma->dfs_bitmap.n_elements = DIV_ROUND_UP(cma_bitmap_maxno(cma), + BITS_PER_BYTE * sizeof(u32)); + debugfs_create_u32_array("bitmap", 0444, tmp, &cma->dfs_bitmap); } static int __init cma_debugfs_init(void) |