[PULL 0/6] Block patches for 6.1-rc0

[PULL 0/6] Block patches for 6.1-rc0

[Max Reitz]

The following changes since commit 7457b407edd6e8555e4b46488aab2f13959fccf8:

  Merge remote-tracking branch 'remotes/thuth-gitlab/tags/pull-request-2021-07-19' into staging (2021-07-19 11:34:08 +0100)

are available in the Git repository at:

  https://github.com/XanClic/qemu.git tags/pull-block-2021-07-19

for you to fetch changes up to 36109bff171ba0811fa4c723cecdf6c3561fa318:

  blkdebug: protect rules and suspended_reqs with a lock (2021-07-19 17:38:38 +0200)

----------------------------------------------------------------
Block patches for 6.1-rc0:
- Make blkdebug's suspend/resume handling robust (and thread-safe)

----------------------------------------------------------------
Emanuele Giuseppe Esposito (6):
  blkdebug: refactor removal of a suspended request
  blkdebug: move post-resume handling to resume_req_by_tag
  blkdebug: track all actions
  blkdebug: do not suspend in the middle of QLIST_FOREACH_SAFE
  block/blkdebug: remove new_state field and instead use a local
    variable
  blkdebug: protect rules and suspended_reqs with a lock

 block/blkdebug.c | 136 ++++++++++++++++++++++++++++++++---------------
 1 file changed, 92 insertions(+), 44 deletions(-)

-- 
2.31.1

[PULL 1/6] blkdebug: refactor removal of a suspended request

[Max Reitz]

From: Emanuele Giuseppe Esposito <eesposit@redhat.com>

Extract to a separate function.  Do not rely on FOREACH_SAFE, which is
only "safe" if the *current* node is removed---not if another node is
removed.  Instead, just walk the entire list from the beginning when
asked to resume all suspended requests with a given tag.

Co-developed-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Emanuele Giuseppe Esposito <eesposit@redhat.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Message-Id: <20210614082931.24925-2-eesposit@redhat.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>
---
 block/blkdebug.c | 33 ++++++++++++++++++++++-----------
 1 file changed, 22 insertions(+), 11 deletions(-)

diff --git a/block/blkdebug.c b/block/blkdebug.c
index 2c0b9b0ee8..5ccbfcab42 100644
--- a/block/blkdebug.c
+++ b/block/blkdebug.c
@@ -793,7 +793,6 @@ static void suspend_request(BlockDriverState *bs, BlkdebugRule *rule)
         printf("blkdebug: Resuming request '%s'\n", r.tag);
     }
 
-    QLIST_REMOVE(&r, next);
     g_free(r.tag);
 }
 
@@ -869,25 +868,40 @@ static int blkdebug_debug_breakpoint(BlockDriverState *bs, const char *event,
     return 0;
 }
 
-static int blkdebug_debug_resume(BlockDriverState *bs, const char *tag)
+static int resume_req_by_tag(BDRVBlkdebugState *s, const char *tag, bool all)
 {
-    BDRVBlkdebugState *s = bs->opaque;
-    BlkdebugSuspendedReq *r, *next;
+    BlkdebugSuspendedReq *r;
 
-    QLIST_FOREACH_SAFE(r, &s->suspended_reqs, next, next) {
+retry:
+    /*
+     * No need for _SAFE, since a different coroutine can remove another node
+     * (not the current one) in this list, and when the current one is removed
+     * the iteration starts back from beginning anyways.
+     */
+    QLIST_FOREACH(r, &s->suspended_reqs, next) {
         if (!strcmp(r->tag, tag)) {
+            QLIST_REMOVE(r, next);
             qemu_coroutine_enter(r->co);
+            if (all) {
+                goto retry;
+            }
             return 0;
         }
     }
     return -ENOENT;
 }
 
+static int blkdebug_debug_resume(BlockDriverState *bs, const char *tag)
+{
+    BDRVBlkdebugState *s = bs->opaque;
+
+    return resume_req_by_tag(s, tag, false);
+}
+
 static int blkdebug_debug_remove_breakpoint(BlockDriverState *bs,
                                             const char *tag)
 {
     BDRVBlkdebugState *s = bs->opaque;
-    BlkdebugSuspendedReq *r, *r_next;
     BlkdebugRule *rule, *next;
     int i, ret = -ENOENT;
 
@@ -900,11 +914,8 @@ static int blkdebug_debug_remove_breakpoint(BlockDriverState *bs,
             }
         }
     }
-    QLIST_FOREACH_SAFE(r, &s->suspended_reqs, next, r_next) {
-        if (!strcmp(r->tag, tag)) {
-            qemu_coroutine_enter(r->co);
-            ret = 0;
-        }
+    if (resume_req_by_tag(s, tag, true) == 0) {
+        ret = 0;
     }
     return ret;
 }
-- 
2.31.1

[PULL 2/6] blkdebug: move post-resume handling to resume_req_by_tag

[Max Reitz]

From: Emanuele Giuseppe Esposito <eesposit@redhat.com>

We want to move qemu_coroutine_yield() after the loop on rules,
because QLIST_FOREACH_SAFE is wrong if the rule list is modified
while the coroutine has yielded.  Therefore move the suspended
request to the heap and clean it up from the remove side.
All that is left is for blkdebug_debug_event to handle the
yielding.

Co-developed-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Emanuele Giuseppe Esposito <eesposit@redhat.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Message-Id: <20210614082931.24925-3-eesposit@redhat.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>
---
 block/blkdebug.c | 31 ++++++++++++++++++-------------
 1 file changed, 18 insertions(+), 13 deletions(-)

diff --git a/block/blkdebug.c b/block/blkdebug.c
index 5ccbfcab42..e8fdf7b056 100644
--- a/block/blkdebug.c
+++ b/block/blkdebug.c
@@ -775,25 +775,20 @@ static void blkdebug_close(BlockDriverState *bs)
 static void suspend_request(BlockDriverState *bs, BlkdebugRule *rule)
 {
     BDRVBlkdebugState *s = bs->opaque;
-    BlkdebugSuspendedReq r;
+    BlkdebugSuspendedReq *r;
 
-    r = (BlkdebugSuspendedReq) {
-        .co         = qemu_coroutine_self(),
-        .tag        = g_strdup(rule->options.suspend.tag),
-    };
+    r = g_new(BlkdebugSuspendedReq, 1);
+
+    r->co         = qemu_coroutine_self();
+    r->tag        = g_strdup(rule->options.suspend.tag);
 
     remove_rule(rule);
-    QLIST_INSERT_HEAD(&s->suspended_reqs, &r, next);
+    QLIST_INSERT_HEAD(&s->suspended_reqs, r, next);
 
     if (!qtest_enabled()) {
-        printf("blkdebug: Suspended request '%s'\n", r.tag);
+        printf("blkdebug: Suspended request '%s'\n", r->tag);
     }
     qemu_coroutine_yield();
-    if (!qtest_enabled()) {
-        printf("blkdebug: Resuming request '%s'\n", r.tag);
-    }
-
-    g_free(r.tag);
 }
 
 static bool process_rule(BlockDriverState *bs, struct BlkdebugRule *rule,
@@ -880,8 +875,18 @@ retry:
      */
     QLIST_FOREACH(r, &s->suspended_reqs, next) {
         if (!strcmp(r->tag, tag)) {
+            Coroutine *co = r->co;
+
+            if (!qtest_enabled()) {
+                printf("blkdebug: Resuming request '%s'\n", r->tag);
+            }
+
             QLIST_REMOVE(r, next);
-            qemu_coroutine_enter(r->co);
+            g_free(r->tag);
+            g_free(r);
+
+            qemu_coroutine_enter(co);
+
             if (all) {
                 goto retry;
             }
-- 
2.31.1

[PULL 3/6] blkdebug: track all actions

[Max Reitz]

From: Emanuele Giuseppe Esposito <eesposit@redhat.com>

Add a counter for each action that a rule can trigger.
This is mainly used to keep track of how many coroutine_yield()
we need to perform after processing all rules in the list.

Co-developed-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Emanuele Giuseppe Esposito <eesposit@redhat.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Message-Id: <20210614082931.24925-4-eesposit@redhat.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>
---
 block/blkdebug.c | 17 ++++++++---------
 1 file changed, 8 insertions(+), 9 deletions(-)

diff --git a/block/blkdebug.c b/block/blkdebug.c
index e8fdf7b056..6bdeb2c7b3 100644
--- a/block/blkdebug.c
+++ b/block/blkdebug.c
@@ -74,6 +74,7 @@ enum {
     ACTION_INJECT_ERROR,
     ACTION_SET_STATE,
     ACTION_SUSPEND,
+    ACTION__MAX,
 };
 
 typedef struct BlkdebugRule {
@@ -791,22 +792,22 @@ static void suspend_request(BlockDriverState *bs, BlkdebugRule *rule)
     qemu_coroutine_yield();
 }
 
-static bool process_rule(BlockDriverState *bs, struct BlkdebugRule *rule,
-    bool injected)
+static void process_rule(BlockDriverState *bs, struct BlkdebugRule *rule,
+                         int *action_count)
 {
     BDRVBlkdebugState *s = bs->opaque;
 
     /* Only process rules for the current state */
     if (rule->state && rule->state != s->state) {
-        return injected;
+        return;
     }
 
     /* Take the action */
+    action_count[rule->action]++;
     switch (rule->action) {
     case ACTION_INJECT_ERROR:
-        if (!injected) {
+        if (action_count[ACTION_INJECT_ERROR] == 1) {
             QSIMPLEQ_INIT(&s->active_rules);
-            injected = true;
         }
         QSIMPLEQ_INSERT_HEAD(&s->active_rules, rule, active_next);
         break;
@@ -819,21 +820,19 @@ static bool process_rule(BlockDriverState *bs, struct BlkdebugRule *rule,
         suspend_request(bs, rule);
         break;
     }
-    return injected;
 }
 
 static void blkdebug_debug_event(BlockDriverState *bs, BlkdebugEvent event)
 {
     BDRVBlkdebugState *s = bs->opaque;
     struct BlkdebugRule *rule, *next;
-    bool injected;
+    int actions_count[ACTION__MAX] = { 0 };
 
     assert((int)event >= 0 && event < BLKDBG__MAX);
 
-    injected = false;
     s->new_state = s->state;
     QLIST_FOREACH_SAFE(rule, &s->rules[event], next, next) {
-        injected = process_rule(bs, rule, injected);
+        process_rule(bs, rule, actions_count);
     }
     s->state = s->new_state;
 }
-- 
2.31.1

[PULL 4/6] blkdebug: do not suspend in the middle of QLIST_FOREACH_SAFE

[Max Reitz]

From: Emanuele Giuseppe Esposito <eesposit@redhat.com>

That would be unsafe in case a rule other than the current one
is removed while the coroutine has yielded.
Keep FOREACH_SAFE because suspend_request deletes the current rule.

After this patch, *all* matching rules are deleted before suspending
the coroutine, rather than just one.
This doesn't affect the existing testcases.

Use actions_count to see how many yield to issue.

Co-developed-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Emanuele Giuseppe Esposito <eesposit@redhat.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Message-Id: <20210614082931.24925-5-eesposit@redhat.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>
---
 block/blkdebug.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/block/blkdebug.c b/block/blkdebug.c
index 6bdeb2c7b3..dd82131d1e 100644
--- a/block/blkdebug.c
+++ b/block/blkdebug.c
@@ -789,7 +789,6 @@ static void suspend_request(BlockDriverState *bs, BlkdebugRule *rule)
     if (!qtest_enabled()) {
         printf("blkdebug: Suspended request '%s'\n", r->tag);
     }
-    qemu_coroutine_yield();
 }
 
 static void process_rule(BlockDriverState *bs, struct BlkdebugRule *rule,
@@ -834,6 +833,12 @@ static void blkdebug_debug_event(BlockDriverState *bs, BlkdebugEvent event)
     QLIST_FOREACH_SAFE(rule, &s->rules[event], next, next) {
         process_rule(bs, rule, actions_count);
     }
+
+    while (actions_count[ACTION_SUSPEND] > 0) {
+        qemu_coroutine_yield();
+        actions_count[ACTION_SUSPEND]--;
+    }
+
     s->state = s->new_state;
 }
 
-- 
2.31.1

[PULL 5/6] block/blkdebug: remove new_state field and instead use a local variable

[Max Reitz]

From: Emanuele Giuseppe Esposito <eesposit@redhat.com>

There seems to be no benefit in using a field. Replace it with a local
variable, and move the state update before the yields.

The state update has do be done before the yields because now using
a local variable does not allow the new updated state to be visible
by the other yields.

Signed-off-by: Emanuele Giuseppe Esposito <eesposit@redhat.com>
Message-Id: <20210614082931.24925-6-eesposit@redhat.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>
---
 block/blkdebug.c | 13 ++++++-------
 1 file changed, 6 insertions(+), 7 deletions(-)

diff --git a/block/blkdebug.c b/block/blkdebug.c
index dd82131d1e..b47c3fd97c 100644
--- a/block/blkdebug.c
+++ b/block/blkdebug.c
@@ -40,7 +40,6 @@
 
 typedef struct BDRVBlkdebugState {
     int state;
-    int new_state;
     uint64_t align;
     uint64_t max_transfer;
     uint64_t opt_write_zero;
@@ -792,7 +791,7 @@ static void suspend_request(BlockDriverState *bs, BlkdebugRule *rule)
 }
 
 static void process_rule(BlockDriverState *bs, struct BlkdebugRule *rule,
-                         int *action_count)
+                         int *action_count, int *new_state)
 {
     BDRVBlkdebugState *s = bs->opaque;
 
@@ -812,7 +811,7 @@ static void process_rule(BlockDriverState *bs, struct BlkdebugRule *rule,
         break;
 
     case ACTION_SET_STATE:
-        s->new_state = rule->options.set_state.new_state;
+        *new_state = rule->options.set_state.new_state;
         break;
 
     case ACTION_SUSPEND:
@@ -825,21 +824,21 @@ static void blkdebug_debug_event(BlockDriverState *bs, BlkdebugEvent event)
 {
     BDRVBlkdebugState *s = bs->opaque;
     struct BlkdebugRule *rule, *next;
+    int new_state;
     int actions_count[ACTION__MAX] = { 0 };
 
     assert((int)event >= 0 && event < BLKDBG__MAX);
 
-    s->new_state = s->state;
+    new_state = s->state;
     QLIST_FOREACH_SAFE(rule, &s->rules[event], next, next) {
-        process_rule(bs, rule, actions_count);
+        process_rule(bs, rule, actions_count, &new_state);
     }
+    s->state = new_state;
 
     while (actions_count[ACTION_SUSPEND] > 0) {
         qemu_coroutine_yield();
         actions_count[ACTION_SUSPEND]--;
     }
-
-    s->state = s->new_state;
 }
 
 static int blkdebug_debug_breakpoint(BlockDriverState *bs, const char *event,
-- 
2.31.1

[PULL 6/6] blkdebug: protect rules and suspended_reqs with a lock

[Max Reitz]

From: Emanuele Giuseppe Esposito <eesposit@redhat.com>

First, categorize the structure fields to identify what needs
to be protected and what doesn't.

We essentially need to protect only .state, and the 3 lists in
BDRVBlkdebugState.

Then, add the lock and mark the functions accordingly.

Co-developed-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Emanuele Giuseppe Esposito <eesposit@redhat.com>
Message-Id: <20210614082931.24925-7-eesposit@redhat.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>
---
 block/blkdebug.c | 49 ++++++++++++++++++++++++++++++++++++++----------
 1 file changed, 39 insertions(+), 10 deletions(-)

diff --git a/block/blkdebug.c b/block/blkdebug.c
index b47c3fd97c..8b67554bec 100644
--- a/block/blkdebug.c
+++ b/block/blkdebug.c
@@ -38,24 +38,27 @@
 #include "qapi/qobject-input-visitor.h"
 #include "sysemu/qtest.h"
 
+/* All APIs are thread-safe */
+
 typedef struct BDRVBlkdebugState {
-    int state;
+    /* IN: initialized in blkdebug_open() and never changed */
     uint64_t align;
     uint64_t max_transfer;
     uint64_t opt_write_zero;
     uint64_t max_write_zero;
     uint64_t opt_discard;
     uint64_t max_discard;
-
+    char *config_file; /* For blkdebug_refresh_filename() */
+    /* initialized in blkdebug_parse_perms() */
     uint64_t take_child_perms;
     uint64_t unshare_child_perms;
 
-    /* For blkdebug_refresh_filename() */
-    char *config_file;
-
+    /* State. Protected by lock */
+    int state;
     QLIST_HEAD(, BlkdebugRule) rules[BLKDBG__MAX];
     QSIMPLEQ_HEAD(, BlkdebugRule) active_rules;
     QLIST_HEAD(, BlkdebugSuspendedReq) suspended_reqs;
+    QemuMutex lock;
 } BDRVBlkdebugState;
 
 typedef struct BlkdebugAIOCB {
@@ -64,8 +67,11 @@ typedef struct BlkdebugAIOCB {
 } BlkdebugAIOCB;
 
 typedef struct BlkdebugSuspendedReq {
+    /* IN: initialized in suspend_request() */
     Coroutine *co;
     char *tag;
+
+    /* List entry protected BDRVBlkdebugState's lock */
     QLIST_ENTRY(BlkdebugSuspendedReq) next;
 } BlkdebugSuspendedReq;
 
@@ -77,6 +83,7 @@ enum {
 };
 
 typedef struct BlkdebugRule {
+    /* IN: initialized in add_rule() or blkdebug_debug_breakpoint() */
     BlkdebugEvent event;
     int action;
     int state;
@@ -95,6 +102,8 @@ typedef struct BlkdebugRule {
             char *tag;
         } suspend;
     } options;
+
+    /* List entries protected BDRVBlkdebugState's lock */
     QLIST_ENTRY(BlkdebugRule) next;
     QSIMPLEQ_ENTRY(BlkdebugRule) active_next;
 } BlkdebugRule;
@@ -244,11 +253,14 @@ static int add_rule(void *opaque, QemuOpts *opts, Error **errp)
     };
 
     /* Add the rule */
+    qemu_mutex_lock(&s->lock);
     QLIST_INSERT_HEAD(&s->rules[event], rule, next);
+    qemu_mutex_unlock(&s->lock);
 
     return 0;
 }
 
+/* Called with lock held or from .bdrv_close */
 static void remove_rule(BlkdebugRule *rule)
 {
     switch (rule->action) {
@@ -467,6 +479,7 @@ static int blkdebug_open(BlockDriverState *bs, QDict *options, int flags,
     int ret;
     uint64_t align;
 
+    qemu_mutex_init(&s->lock);
     opts = qemu_opts_create(&runtime_opts, NULL, 0, &error_abort);
     if (!qemu_opts_absorb_qdict(opts, options, errp)) {
         ret = -EINVAL;
@@ -567,6 +580,7 @@ static int blkdebug_open(BlockDriverState *bs, QDict *options, int flags,
     ret = 0;
 out:
     if (ret < 0) {
+        qemu_mutex_destroy(&s->lock);
         g_free(s->config_file);
     }
     qemu_opts_del(opts);
@@ -581,6 +595,7 @@ static int rule_check(BlockDriverState *bs, uint64_t offset, uint64_t bytes,
     int error;
     bool immediately;
 
+    qemu_mutex_lock(&s->lock);
     QSIMPLEQ_FOREACH(rule, &s->active_rules, active_next) {
         uint64_t inject_offset = rule->options.inject.offset;
 
@@ -594,6 +609,7 @@ static int rule_check(BlockDriverState *bs, uint64_t offset, uint64_t bytes,
     }
 
     if (!rule || !rule->options.inject.error) {
+        qemu_mutex_unlock(&s->lock);
         return 0;
     }
 
@@ -605,6 +621,7 @@ static int rule_check(BlockDriverState *bs, uint64_t offset, uint64_t bytes,
         remove_rule(rule);
     }
 
+    qemu_mutex_unlock(&s->lock);
     if (!immediately) {
         aio_co_schedule(qemu_get_current_aio_context(), qemu_coroutine_self());
         qemu_coroutine_yield();
@@ -770,8 +787,10 @@ static void blkdebug_close(BlockDriverState *bs)
     }
 
     g_free(s->config_file);
+    qemu_mutex_destroy(&s->lock);
 }
 
+/* Called with lock held.  */
 static void suspend_request(BlockDriverState *bs, BlkdebugRule *rule)
 {
     BDRVBlkdebugState *s = bs->opaque;
@@ -790,6 +809,7 @@ static void suspend_request(BlockDriverState *bs, BlkdebugRule *rule)
     }
 }
 
+/* Called with lock held.  */
 static void process_rule(BlockDriverState *bs, struct BlkdebugRule *rule,
                          int *action_count, int *new_state)
 {
@@ -829,11 +849,13 @@ static void blkdebug_debug_event(BlockDriverState *bs, BlkdebugEvent event)
 
     assert((int)event >= 0 && event < BLKDBG__MAX);
 
-    new_state = s->state;
-    QLIST_FOREACH_SAFE(rule, &s->rules[event], next, next) {
-        process_rule(bs, rule, actions_count, &new_state);
+    WITH_QEMU_LOCK_GUARD(&s->lock) {
+        new_state = s->state;
+        QLIST_FOREACH_SAFE(rule, &s->rules[event], next, next) {
+            process_rule(bs, rule, actions_count, &new_state);
+        }
+        s->state = new_state;
     }
-    s->state = new_state;
 
     while (actions_count[ACTION_SUSPEND] > 0) {
         qemu_coroutine_yield();
@@ -861,11 +883,14 @@ static int blkdebug_debug_breakpoint(BlockDriverState *bs, const char *event,
         .options.suspend.tag = g_strdup(tag),
     };
 
+    qemu_mutex_lock(&s->lock);
     QLIST_INSERT_HEAD(&s->rules[blkdebug_event], rule, next);
+    qemu_mutex_unlock(&s->lock);
 
     return 0;
 }
 
+/* Called with lock held. May temporarily release lock. */
 static int resume_req_by_tag(BDRVBlkdebugState *s, const char *tag, bool all)
 {
     BlkdebugSuspendedReq *r;
@@ -888,7 +913,9 @@ retry:
             g_free(r->tag);
             g_free(r);
 
+            qemu_mutex_unlock(&s->lock);
             qemu_coroutine_enter(co);
+            qemu_mutex_lock(&s->lock);
 
             if (all) {
                 goto retry;
@@ -902,7 +929,7 @@ retry:
 static int blkdebug_debug_resume(BlockDriverState *bs, const char *tag)
 {
     BDRVBlkdebugState *s = bs->opaque;
-
+    QEMU_LOCK_GUARD(&s->lock);
     return resume_req_by_tag(s, tag, false);
 }
 
@@ -913,6 +940,7 @@ static int blkdebug_debug_remove_breakpoint(BlockDriverState *bs,
     BlkdebugRule *rule, *next;
     int i, ret = -ENOENT;
 
+    QEMU_LOCK_GUARD(&s->lock);
     for (i = 0; i < BLKDBG__MAX; i++) {
         QLIST_FOREACH_SAFE(rule, &s->rules[i], next, next) {
             if (rule->action == ACTION_SUSPEND &&
@@ -933,6 +961,7 @@ static bool blkdebug_debug_is_suspended(BlockDriverState *bs, const char *tag)
     BDRVBlkdebugState *s = bs->opaque;
     BlkdebugSuspendedReq *r;
 
+    QEMU_LOCK_GUARD(&s->lock);
     QLIST_FOREACH(r, &s->suspended_reqs, next) {
         if (!strcmp(r->tag, tag)) {
             return true;
-- 
2.31.1

Re: [PULL 0/6] Block patches for 6.1-rc0

[Peter Maydell]

On Mon, 19 Jul 2021 at 18:27, Max Reitz <mreitz@redhat.com> wrote:
>
> The following changes since commit 7457b407edd6e8555e4b46488aab2f13959fccf8:
>
>   Merge remote-tracking branch 'remotes/thuth-gitlab/tags/pull-request-2021-07-19' into staging (2021-07-19 11:34:08 +0100)
>
> are available in the Git repository at:
>
>   https://github.com/XanClic/qemu.git tags/pull-block-2021-07-19
>
> for you to fetch changes up to 36109bff171ba0811fa4c723cecdf6c3561fa318:
>
>   blkdebug: protect rules and suspended_reqs with a lock (2021-07-19 17:38:38 +0200)
>
> ----------------------------------------------------------------
> Block patches for 6.1-rc0:
> - Make blkdebug's suspend/resume handling robust (and thread-safe)
>


Applied, thanks.

Please update the changelog at https://wiki.qemu.org/ChangeLog/6.1
for any user-visible changes.

-- PMM