* [PATCH 2/3] UBI: wl: Rename cancel flag to shutdown
2014-09-22 8:45 [PATCH 1/3] UBI: ubi_eba_read_leb: Remove in vain variable assignment Richard Weinberger
@ 2014-09-22 8:45 ` Richard Weinberger
2014-09-22 8:45 ` [PATCH 3/3] UBI: Fix possible deadlock in erase_worker() Richard Weinberger
2014-09-26 10:46 ` [PATCH 1/3] UBI: ubi_eba_read_leb: Remove in vain variable assignment Artem Bityutskiy
2 siblings, 0 replies; 6+ messages in thread
From: Richard Weinberger @ 2014-09-22 8:45 UTC (permalink / raw)
To: dedekind1; +Cc: linux-mtd, linux-kernel, Richard Weinberger
It confused me more than once that the cancel flag of the
work function does not indicate the cancellation of a single work.
In fact it indicates the WL sub-system shutdown and therefore
worker functions have to free their wl_entries too.
That's why you cannot cancel a single work, you can only shutdown
all works.
Signed-off-by: Richard Weinberger <richard@nod.at>
---
drivers/mtd/ubi/ubi.h | 9 +++++----
drivers/mtd/ubi/wl.c | 24 +++++++++++++-----------
2 files changed, 18 insertions(+), 15 deletions(-)
diff --git a/drivers/mtd/ubi/ubi.h b/drivers/mtd/ubi/ubi.h
index 7bf4163..7dad704 100644
--- a/drivers/mtd/ubi/ubi.h
+++ b/drivers/mtd/ubi/ubi.h
@@ -713,14 +713,15 @@ struct ubi_attach_info {
* @torture: if the physical eraseblock has to be tortured
* @anchor: produce a anchor PEB to by used by fastmap
*
- * The @func pointer points to the worker function. If the @cancel argument is
- * not zero, the worker has to free the resources and exit immediately. The
- * worker has to return zero in case of success and a negative error code in
+ * The @func pointer points to the worker function. If the @shutdown argument is
+ * not zero, the worker has to free the resources and exit immediately as the
+ * WL sub-system is shutting down.
+ * The worker has to return zero in case of success and a negative error code in
* case of failure.
*/
struct ubi_work {
struct list_head list;
- int (*func)(struct ubi_device *ubi, struct ubi_work *wrk, int cancel);
+ int (*func)(struct ubi_device *ubi, struct ubi_work *wrk, int shutdown);
/* The below fields are only relevant to erasure works */
struct ubi_wl_entry *e;
int vol_id;
diff --git a/drivers/mtd/ubi/wl.c b/drivers/mtd/ubi/wl.c
index 20f4917..253ec9b 100644
--- a/drivers/mtd/ubi/wl.c
+++ b/drivers/mtd/ubi/wl.c
@@ -864,7 +864,7 @@ static void schedule_ubi_work(struct ubi_device *ubi, struct ubi_work *wrk)
}
static int erase_worker(struct ubi_device *ubi, struct ubi_work *wl_wrk,
- int cancel);
+ int shutdown);
#ifdef CONFIG_MTD_UBI_FASTMAP
/**
@@ -990,14 +990,15 @@ int ubi_wl_put_fm_peb(struct ubi_device *ubi, struct ubi_wl_entry *fm_e,
* wear_leveling_worker - wear-leveling worker function.
* @ubi: UBI device description object
* @wrk: the work object
- * @cancel: non-zero if the worker has to free memory and exit
+ * @shutdown: non-zero if the worker has to free memory and exit
+ * because the WL-subsystem is shutting down
*
* This function copies a more worn out physical eraseblock to a less worn out
* one. Returns zero in case of success and a negative error code in case of
* failure.
*/
static int wear_leveling_worker(struct ubi_device *ubi, struct ubi_work *wrk,
- int cancel)
+ int shutdown)
{
int err, scrubbing = 0, torture = 0, protect = 0, erroneous = 0;
int vol_id = -1, uninitialized_var(lnum);
@@ -1008,7 +1009,7 @@ static int wear_leveling_worker(struct ubi_device *ubi, struct ubi_work *wrk,
struct ubi_vid_hdr *vid_hdr;
kfree(wrk);
- if (cancel)
+ if (shutdown)
return 0;
vid_hdr = ubi_zalloc_vid_hdr(ubi, GFP_NOFS);
@@ -1407,7 +1408,8 @@ int ubi_ensure_anchor_pebs(struct ubi_device *ubi)
* erase_worker - physical eraseblock erase worker function.
* @ubi: UBI device description object
* @wl_wrk: the work object
- * @cancel: non-zero if the worker has to free memory and exit
+ * @shutdown: non-zero if the worker has to free memory and exit
+ * because the WL sub-system is shutting down
*
* This function erases a physical eraseblock and perform torture testing if
* needed. It also takes care about marking the physical eraseblock bad if
@@ -1415,7 +1417,7 @@ int ubi_ensure_anchor_pebs(struct ubi_device *ubi)
* failure.
*/
static int erase_worker(struct ubi_device *ubi, struct ubi_work *wl_wrk,
- int cancel)
+ int shutdown)
{
struct ubi_wl_entry *e = wl_wrk->e;
int pnum = e->pnum;
@@ -1423,7 +1425,7 @@ static int erase_worker(struct ubi_device *ubi, struct ubi_work *wl_wrk,
int lnum = wl_wrk->lnum;
int err, available_consumed = 0;
- if (cancel) {
+ if (shutdown) {
dbg_wl("cancel erasure of PEB %d EC %d", pnum, e->ec);
kfree(wl_wrk);
kmem_cache_free(ubi_wl_entry_slab, e);
@@ -1845,10 +1847,10 @@ int ubi_thread(void *u)
}
/**
- * cancel_pending - cancel all pending works.
+ * shutdown_work - shutdown all pending works.
* @ubi: UBI device description object
*/
-static void cancel_pending(struct ubi_device *ubi)
+static void shutdown_work(struct ubi_device *ubi)
{
while (!list_empty(&ubi->works)) {
struct ubi_work *wrk;
@@ -1997,7 +1999,7 @@ int ubi_wl_init(struct ubi_device *ubi, struct ubi_attach_info *ai)
return 0;
out_free:
- cancel_pending(ubi);
+ shutdown_work(ubi);
tree_destroy(&ubi->used);
tree_destroy(&ubi->free);
tree_destroy(&ubi->scrub);
@@ -2029,7 +2031,7 @@ static void protection_queue_destroy(struct ubi_device *ubi)
void ubi_wl_close(struct ubi_device *ubi)
{
dbg_wl("close the WL sub-system");
- cancel_pending(ubi);
+ shutdown_work(ubi);
protection_queue_destroy(ubi);
tree_destroy(&ubi->used);
tree_destroy(&ubi->erroneous);
--
1.8.4.5
^ permalink raw reply related [flat|nested] 6+ messages in thread* [PATCH 3/3] UBI: Fix possible deadlock in erase_worker()
2014-09-22 8:45 [PATCH 1/3] UBI: ubi_eba_read_leb: Remove in vain variable assignment Richard Weinberger
2014-09-22 8:45 ` [PATCH 2/3] UBI: wl: Rename cancel flag to shutdown Richard Weinberger
@ 2014-09-22 8:45 ` Richard Weinberger
2014-09-26 10:40 ` Artem Bityutskiy
2014-09-26 10:46 ` [PATCH 1/3] UBI: ubi_eba_read_leb: Remove in vain variable assignment Artem Bityutskiy
2 siblings, 1 reply; 6+ messages in thread
From: Richard Weinberger @ 2014-09-22 8:45 UTC (permalink / raw)
To: dedekind1; +Cc: linux-mtd, linux-kernel, Richard Weinberger
If sync_erase() fails with EINTR, ENOMEM, EAGAIN or
EBUSY erase_worker() re-schedules the failed work.
This will lead to a deadlock because erase_worker() is called
with work_sem held in read mode. And schedule_erase() will take
this lock again.
Signed-off-by: Richard Weinberger <richard@nod.at>
---
drivers/mtd/ubi/wl.c | 12 ++----------
1 file changed, 2 insertions(+), 10 deletions(-)
diff --git a/drivers/mtd/ubi/wl.c b/drivers/mtd/ubi/wl.c
index 253ec9b..637ffff 100644
--- a/drivers/mtd/ubi/wl.c
+++ b/drivers/mtd/ubi/wl.c
@@ -1421,8 +1421,6 @@ static int erase_worker(struct ubi_device *ubi, struct ubi_work *wl_wrk,
{
struct ubi_wl_entry *e = wl_wrk->e;
int pnum = e->pnum;
- int vol_id = wl_wrk->vol_id;
- int lnum = wl_wrk->lnum;
int err, available_consumed = 0;
if (shutdown) {
@@ -1459,21 +1457,15 @@ static int erase_worker(struct ubi_device *ubi, struct ubi_work *wl_wrk,
}
ubi_err("failed to erase PEB %d, error %d", pnum, err);
- kfree(wl_wrk);
if (err == -EINTR || err == -ENOMEM || err == -EAGAIN ||
err == -EBUSY) {
- int err1;
-
/* Re-schedule the LEB for erasure */
- err1 = schedule_erase(ubi, e, vol_id, lnum, 0);
- if (err1) {
- err = err1;
- goto out_ro;
- }
+ __schedule_ubi_work(ubi, wl_wrk);
return err;
}
+ kfree(wl_wrk);
kmem_cache_free(ubi_wl_entry_slab, e);
if (err != -EIO)
/*
--
1.8.4.5
^ permalink raw reply related [flat|nested] 6+ messages in thread