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Subject[PATCH] fuse: freezing abort when use wait_event_killable{,_exclusive}().
Date
Freezing process can abort when a client is waiting uninterruptibly
for a response. Add new macro wait_fatal_freezable to try to fix it.

Signed-off-by: cuilifei <cuilifei@xiaomi.com>
---
fs/fuse/dev.c | 30 ++++++++++++++++++++++++++----
include/linux/freezer.h | 26 ++++++++++++++++++++++++++
2 files changed, 52 insertions(+), 4 deletions(-)

diff --git a/fs/fuse/dev.c b/fs/fuse/dev.c
index 70ea57c..e33a081 100644
--- a/fs/fuse/dev.c
+++ b/fs/fuse/dev.c
@@ -19,6 +19,7 @@
#include <linux/pipe_fs_i.h>
#include <linux/swap.h>
#include <linux/splice.h>
+#include <linux/freezer.h>

MODULE_ALIAS_MISCDEV(FUSE_MINOR);
MODULE_ALIAS("devname:fuse");
@@ -99,6 +100,19 @@ void fuse_request_free(struct fuse_req *req)
kmem_cache_free(fuse_req_cachep, req);
}

+static void block_sigs(sigset_t *oldset)
+{
+ sigset_t mask;
+
+ siginitsetinv(&mask, sigmask(SIGKILL));
+ sigprocmask(SIG_BLOCK, &mask, oldset);
+}
+
+static void restore_sigs(sigset_t *oldset)
+{
+ sigprocmask(SIG_SETMASK, oldset, NULL);
+}
+
void __fuse_get_request(struct fuse_req *req)
{
atomic_inc(&req->count);
@@ -134,13 +148,18 @@ static struct fuse_req *__fuse_get_req(struct fuse_conn *fc, unsigned npages,
bool for_background)
{
struct fuse_req *req;
+ sigset_t oldset;
+ int intr;
int err;
atomic_inc(&fc->num_waiting);

if (fuse_block_alloc(fc, for_background)) {
err = -EINTR;
- if (wait_event_killable_exclusive(fc->blocked_waitq,
- !fuse_block_alloc(fc, for_background)))
+ block_sigs(&oldset);
+ intr = wait_fatal_freezable(fc->blocked_waitq,
+ !fuse_block_alloc(fc, for_background), true);
+ restore_sigs(&oldset);
+ if (intr)
goto out;
}
/* Matches smp_wmb() in fuse_set_initialized() */
@@ -427,9 +446,12 @@ static void request_wait_answer(struct fuse_conn *fc, struct fuse_req *req)
}

if (!test_bit(FR_FORCE, &req->flags)) {
+ sigset_t oldset;
/* Only fatal signals may interrupt this */
- err = wait_event_killable(req->waitq,
- test_bit(FR_FINISHED, &req->flags));
+ block_sigs(&oldset);
+ err = wait_fatal_freezable(req->waitq,
+ test_bit(FR_FINISHED, &req->flags), false);
+ restore_sigs(&oldset);
if (!err)
return;

diff --git a/include/linux/freezer.h b/include/linux/freezer.h
index dd03e83..2504cd0 100644
--- a/include/linux/freezer.h
+++ b/include/linux/freezer.h
@@ -256,6 +256,22 @@ static inline int freezable_schedule_hrtimeout_range(ktime_t *expires,
__retval; \
})

+#define wait_fatal_freezable(wq, condition, exclusive) \
+({ \
+ int __ret = 0; \
+ do { \
+ if (exclusive) \
+ __ret = wait_event_interruptible_exclusive(wq, \
+ condition); \
+ else \
+ __ret = wait_event_interruptible(wq, \
+ condition); \
+ if (!__ret || fatal_signal_pending(current)) \
+ break; \
+ } while (try_to_freeze()); \
+ __ret; \
+})
+
#else /* !CONFIG_FREEZER */
static inline bool frozen(struct task_struct *p) { return false; }
static inline bool freezing(struct task_struct *p) { return false; }
@@ -296,6 +312,16 @@ static inline void set_freezable(void) {}
#define wait_event_freezekillable_unsafe(wq, condition) \
wait_event_killable(wq, condition)

+#define wait_fatal_freezable(wq, condition, exclusive) \
+({ \
+ int __ret = 0; \
+ if (exclusive) \
+ __ret = wait_event_killable_exclusive(wq, condition); \
+ else \
+ __ret = wait_event_killable(wq, condition); \
+ __ret; \
+})
+
#endif /* !CONFIG_FREEZER */

#endif /* FREEZER_H_INCLUDED */
--
1.9.1
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