Messages in this thread Patch in this message | | | From | Xin Hao <> | Subject | [PATCH v2 2/2] mm/damon/dbgfs: Add adaptive_targets list check before enable monitor_on | Date | Tue, 19 Oct 2021 22:26:04 +0800 |
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When the ctx->adaptive_targets list is empty, i did some test on monitor_on interface like this.
echo on > /sys/kernel/debug/damon/monitor_on [ 851.988307] damon: kdamond (5390) starts
Though the ctx->adaptive_targets list is empty, but the kthread_run still be called, and the kdamond.x thread still be created, this is meaningless.
So there adds a judgment in 'dbgfs_monitor_on_write', if the ctx->adaptive_targets list is empty, return -EINVAL.
Signed-off-by: Xin Hao <xhao@linux.alibaba.com> --- include/linux/damon.h | 1 + mm/damon/core.c | 5 +++++ mm/damon/dbgfs.c | 10 ++++++++-- 3 files changed, 14 insertions(+), 2 deletions(-)
diff --git a/include/linux/damon.h b/include/linux/damon.h index 715dadd21f7c..06acf73fe9db 100644 --- a/include/linux/damon.h +++ b/include/linux/damon.h @@ -316,6 +316,7 @@ void damon_destroy_scheme(struct damos *s);
struct damon_target *damon_new_target(unsigned long id); void damon_add_target(struct damon_ctx *ctx, struct damon_target *t); +int damon_target_empty(struct damon_ctx *ctx); void damon_free_target(struct damon_target *t); void damon_destroy_target(struct damon_target *t); unsigned int damon_nr_regions(struct damon_target *t); diff --git a/mm/damon/core.c b/mm/damon/core.c index 2f6785737902..c651b49249e5 100644 --- a/mm/damon/core.c +++ b/mm/damon/core.c @@ -156,6 +156,11 @@ void damon_add_target(struct damon_ctx *ctx, struct damon_target *t) list_add_tail(&t->list, &ctx->adaptive_targets); }
+int damon_target_empty(struct damon_ctx *ctx) +{ + return list_empty(&ctx->adaptive_targets); +} + static void damon_del_target(struct damon_target *t) { list_del(&t->list); diff --git a/mm/damon/dbgfs.c b/mm/damon/dbgfs.c index 38188347d8ab..bac42dd358d1 100644 --- a/mm/damon/dbgfs.c +++ b/mm/damon/dbgfs.c @@ -865,9 +865,15 @@ static ssize_t dbgfs_monitor_on_write(struct file *file, return -EINVAL; }
- if (!strncmp(kbuf, "on", count)) + if (!strncmp(kbuf, "on", count)) { + int i; + + for (i = 0; i < dbgfs_nr_ctxs; i++) { + if (damon_target_empty(dbgfs_ctxs[i])) + return -EINVAL; + } err = damon_start(dbgfs_ctxs, dbgfs_nr_ctxs); - else if (!strncmp(kbuf, "off", count)) + } else if (!strncmp(kbuf, "off", count)) err = damon_stop(dbgfs_ctxs, dbgfs_nr_ctxs); else err = -EINVAL; -- 2.31.0
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