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Subject[PATCH 2/2] mm/damon/dbgfs: Fix missed use of damon_dbgfs_lock
Date
DAMON debugfs is supposed to protect dbgfs_ctxs, dbgfs_nr_ctxs, and
dbgfs_dirs using damon_dbgfs_lock. However, some of the code is
accessing the variables without the protection. This commit fixes it by
protecting all such accesses.

Fixes: 75c1c2b53c78 ("mm/damon/dbgfs: support multiple contexts")
Signed-off-by: SeongJae Park <sj@kernel.org>
---
mm/damon/dbgfs.c | 12 +++++++++---
1 file changed, 9 insertions(+), 3 deletions(-)

diff --git a/mm/damon/dbgfs.c b/mm/damon/dbgfs.c
index 8ce1311ac533..9b520bb4a3e7 100644
--- a/mm/damon/dbgfs.c
+++ b/mm/damon/dbgfs.c
@@ -877,12 +877,14 @@ static ssize_t dbgfs_monitor_on_write(struct file *file,
return -EINVAL;
}

+ mutex_lock(&damon_dbgfs_lock);
if (!strncmp(kbuf, "on", count)) {
int i;

for (i = 0; i < dbgfs_nr_ctxs; i++) {
if (damon_targets_empty(dbgfs_ctxs[i])) {
kfree(kbuf);
+ mutex_unlock(&damon_dbgfs_lock);
return -EINVAL;
}
}
@@ -892,6 +894,7 @@ static ssize_t dbgfs_monitor_on_write(struct file *file,
} else {
ret = -EINVAL;
}
+ mutex_unlock(&damon_dbgfs_lock);

if (!ret)
ret = count;
@@ -944,15 +947,16 @@ static int __init __damon_dbgfs_init(void)

static int __init damon_dbgfs_init(void)
{
- int rc;
+ int rc = -ENOMEM;

+ mutex_lock(&damon_dbgfs_lock);
dbgfs_ctxs = kmalloc(sizeof(*dbgfs_ctxs), GFP_KERNEL);
if (!dbgfs_ctxs)
- return -ENOMEM;
+ goto out;
dbgfs_ctxs[0] = dbgfs_new_ctx();
if (!dbgfs_ctxs[0]) {
kfree(dbgfs_ctxs);
- return -ENOMEM;
+ goto out;
}
dbgfs_nr_ctxs = 1;

@@ -963,6 +967,8 @@ static int __init damon_dbgfs_init(void)
pr_err("%s: dbgfs init failed\n", __func__);
}

+out:
+ mutex_unlock(&damon_dbgfs_lock);
return rc;
}

--
2.17.1
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