| Message ID | 20240207115902.371649-1-jiri@resnulli.us (mailing list archive) |
|---|---|
| State | Accepted |
| Commit | 53c0441dd2c44ee93fddb5473885fd41e4bc2361 |
| Delegated to: | Netdev Maintainers |
| Headers | show |
| Series | [net,v2] dpll: fix possible deadlock during netlink dump operation | expand |
>From: Jiri Pirko <jiri@resnulli.us> >Sent: Wednesday, February 7, 2024 12:59 PM > >From: Jiri Pirko <jiri@nvidia.com> > >Recently, I've been hitting following deadlock warning during dpll pin >dump: > >[52804.637962] ====================================================== >[52804.638536] WARNING: possible circular locking dependency detected >[52804.639111] 6.8.0-rc2jiri+ #1 Not tainted >[52804.639529] ------------------------------------------------------ >[52804.640104] python3/2984 is trying to acquire lock: >[52804.640581] ffff88810e642678 (nlk_cb_mutex-GENERIC){+.+.}-{3:3}, at: >netlink_dump+0xb3/0x780 >[52804.641417] > but task is already holding lock: >[52804.642010] ffffffff83bde4c8 (dpll_lock){+.+.}-{3:3}, at: >dpll_lock_dumpit+0x13/0x20 >[52804.642747] > which lock already depends on the new lock. > >[52804.643551] > the existing dependency chain (in reverse order) is: >[52804.644259] > -> #1 (dpll_lock){+.+.}-{3:3}: >[52804.644836] lock_acquire+0x174/0x3e0 >[52804.645271] __mutex_lock+0x119/0x1150 >[52804.645723] dpll_lock_dumpit+0x13/0x20 >[52804.646169] genl_start+0x266/0x320 >[52804.646578] __netlink_dump_start+0x321/0x450 >[52804.647056] genl_family_rcv_msg_dumpit+0x155/0x1e0 >[52804.647575] genl_rcv_msg+0x1ed/0x3b0 >[52804.648001] netlink_rcv_skb+0xdc/0x210 >[52804.648440] genl_rcv+0x24/0x40 >[52804.648831] netlink_unicast+0x2f1/0x490 >[52804.649290] netlink_sendmsg+0x36d/0x660 >[52804.649742] __sock_sendmsg+0x73/0xc0 >[52804.650165] __sys_sendto+0x184/0x210 >[52804.650597] __x64_sys_sendto+0x72/0x80 >[52804.651045] do_syscall_64+0x6f/0x140 >[52804.651474] entry_SYSCALL_64_after_hwframe+0x46/0x4e >[52804.652001] > -> #0 (nlk_cb_mutex-GENERIC){+.+.}-{3:3}: >[52804.652650] check_prev_add+0x1ae/0x1280 >[52804.653107] __lock_acquire+0x1ed3/0x29a0 >[52804.653559] lock_acquire+0x174/0x3e0 >[52804.653984] __mutex_lock+0x119/0x1150 >[52804.654423] netlink_dump+0xb3/0x780 >[52804.654845] __netlink_dump_start+0x389/0x450 >[52804.655321] genl_family_rcv_msg_dumpit+0x155/0x1e0 >[52804.655842] genl_rcv_msg+0x1ed/0x3b0 >[52804.656272] netlink_rcv_skb+0xdc/0x210 >[52804.656721] genl_rcv+0x24/0x40 >[52804.657119] netlink_unicast+0x2f1/0x490 >[52804.657570] netlink_sendmsg+0x36d/0x660 >[52804.658022] __sock_sendmsg+0x73/0xc0 >[52804.658450] __sys_sendto+0x184/0x210 >[52804.658877] __x64_sys_sendto+0x72/0x80 >[52804.659322] do_syscall_64+0x6f/0x140 >[52804.659752] entry_SYSCALL_64_after_hwframe+0x46/0x4e >[52804.660281] > other info that might help us debug this: > >[52804.661077] Possible unsafe locking scenario: > >[52804.661671] CPU0 CPU1 >[52804.662129] ---- ---- >[52804.662577] lock(dpll_lock); >[52804.662924] lock(nlk_cb_mutex-GENERIC); >[52804.663538] lock(dpll_lock); >[52804.664073] lock(nlk_cb_mutex-GENERIC); >[52804.664490] > >The issue as follows: __netlink_dump_start() calls control->start(cb) >with nlk->cb_mutex held. In control->start(cb) the dpll_lock is taken. >Then nlk->cb_mutex is released and taken again in netlink_dump(), while >dpll_lock still being held. That leads to ABBA deadlock when another >CPU races with the same operation. > >Fix this by moving dpll_lock taking into dumpit() callback which ensures >correct lock taking order. > >Fixes: 9d71b54b65b1 ("dpll: netlink: Add DPLL framework base functions") >Signed-off-by: Jiri Pirko <jiri@nvidia.com> >--- LGTM, Thank you! Reviewed-by: Arkadiusz Kubalewski <arkadiusz.kubalewski@intel.com> >v1->v2: >- fixed in dpll.yaml and regenerated c/h files >--- > Documentation/netlink/specs/dpll.yaml | 4 ---- > drivers/dpll/dpll_netlink.c | 20 ++++++-------------- > drivers/dpll/dpll_nl.c | 4 ---- > drivers/dpll/dpll_nl.h | 2 -- > 4 files changed, 6 insertions(+), 24 deletions(-) > >diff --git a/Documentation/netlink/specs/dpll.yaml >b/Documentation/netlink/specs/dpll.yaml >index b14aed18065f..3dcc9ece272a 100644 >--- a/Documentation/netlink/specs/dpll.yaml >+++ b/Documentation/netlink/specs/dpll.yaml >@@ -384,8 +384,6 @@ operations: > - type > > dump: >- pre: dpll-lock-dumpit >- post: dpll-unlock-dumpit > reply: *dev-attrs > > - >@@ -473,8 +471,6 @@ operations: > - fractional-frequency-offset > > dump: >- pre: dpll-lock-dumpit >- post: dpll-unlock-dumpit > request: > attributes: > - id >diff --git a/drivers/dpll/dpll_netlink.c b/drivers/dpll/dpll_netlink.c >index 314bb3775465..4ca9ad16cd95 100644 >--- a/drivers/dpll/dpll_netlink.c >+++ b/drivers/dpll/dpll_netlink.c >@@ -1199,6 +1199,7 @@ int dpll_nl_pin_get_dumpit(struct sk_buff *skb, >struct netlink_callback *cb) > unsigned long i; > int ret = 0; > >+ mutex_lock(&dpll_lock); > xa_for_each_marked_start(&dpll_pin_xa, i, pin, DPLL_REGISTERED, > ctx->idx) { > if (!dpll_pin_available(pin)) >@@ -1218,6 +1219,8 @@ int dpll_nl_pin_get_dumpit(struct sk_buff *skb, >struct netlink_callback *cb) > } > genlmsg_end(skb, hdr); > } >+ mutex_unlock(&dpll_lock); >+ > if (ret == -EMSGSIZE) { > ctx->idx = i; > return skb->len; >@@ -1373,6 +1376,7 @@ int dpll_nl_device_get_dumpit(struct sk_buff *skb, >struct netlink_callback *cb) > unsigned long i; > int ret = 0; > >+ mutex_lock(&dpll_lock); > xa_for_each_marked_start(&dpll_device_xa, i, dpll, DPLL_REGISTERED, > ctx->idx) { > hdr = genlmsg_put(skb, NETLINK_CB(cb->skb).portid, >@@ -1389,6 +1393,8 @@ int dpll_nl_device_get_dumpit(struct sk_buff *skb, >struct netlink_callback *cb) > } > genlmsg_end(skb, hdr); > } >+ mutex_unlock(&dpll_lock); >+ > if (ret == -EMSGSIZE) { > ctx->idx = i; > return skb->len; >@@ -1439,20 +1445,6 @@ dpll_unlock_doit(const struct genl_split_ops *ops, >struct sk_buff *skb, > mutex_unlock(&dpll_lock); > } > >-int dpll_lock_dumpit(struct netlink_callback *cb) >-{ >- mutex_lock(&dpll_lock); >- >- return 0; >-} >- >-int dpll_unlock_dumpit(struct netlink_callback *cb) >-{ >- mutex_unlock(&dpll_lock); >- >- return 0; >-} >- > int dpll_pin_pre_doit(const struct genl_split_ops *ops, struct sk_buff >*skb, > struct genl_info *info) > { >diff --git a/drivers/dpll/dpll_nl.c b/drivers/dpll/dpll_nl.c >index eaee5be7aa64..1e95f5397cfc 100644 >--- a/drivers/dpll/dpll_nl.c >+++ b/drivers/dpll/dpll_nl.c >@@ -95,9 +95,7 @@ static const struct genl_split_ops dpll_nl_ops[] = { > }, > { > .cmd = DPLL_CMD_DEVICE_GET, >- .start = dpll_lock_dumpit, > .dumpit = dpll_nl_device_get_dumpit, >- .done = dpll_unlock_dumpit, > .flags = GENL_ADMIN_PERM | GENL_CMD_CAP_DUMP, > }, > { >@@ -129,9 +127,7 @@ static const struct genl_split_ops dpll_nl_ops[] = { > }, > { > .cmd = DPLL_CMD_PIN_GET, >- .start = dpll_lock_dumpit, > .dumpit = dpll_nl_pin_get_dumpit, >- .done = dpll_unlock_dumpit, > .policy = dpll_pin_get_dump_nl_policy, > .maxattr = DPLL_A_PIN_ID, > .flags = GENL_ADMIN_PERM | GENL_CMD_CAP_DUMP, >diff --git a/drivers/dpll/dpll_nl.h b/drivers/dpll/dpll_nl.h >index 92d4c9c4f788..f491262bee4f 100644 >--- a/drivers/dpll/dpll_nl.h >+++ b/drivers/dpll/dpll_nl.h >@@ -30,8 +30,6 @@ dpll_post_doit(const struct genl_split_ops *ops, struct >sk_buff *skb, > void > dpll_pin_post_doit(const struct genl_split_ops *ops, struct sk_buff *skb, > struct genl_info *info); >-int dpll_lock_dumpit(struct netlink_callback *cb); >-int dpll_unlock_dumpit(struct netlink_callback *cb); > > int dpll_nl_device_id_get_doit(struct sk_buff *skb, struct genl_info >*info); > int dpll_nl_device_get_doit(struct sk_buff *skb, struct genl_info *info); >-- >2.43.0
Hello: This patch was applied to netdev/net.git (main) by Jakub Kicinski <kuba@kernel.org>: On Wed, 7 Feb 2024 12:59:02 +0100 you wrote: > From: Jiri Pirko <jiri@nvidia.com> > > Recently, I've been hitting following deadlock warning during dpll pin > dump: > > [52804.637962] ====================================================== > [52804.638536] WARNING: possible circular locking dependency detected > [52804.639111] 6.8.0-rc2jiri+ #1 Not tainted > [52804.639529] ------------------------------------------------------ > [52804.640104] python3/2984 is trying to acquire lock: > [52804.640581] ffff88810e642678 (nlk_cb_mutex-GENERIC){+.+.}-{3:3}, at: netlink_dump+0xb3/0x780 > [52804.641417] > but task is already holding lock: > [52804.642010] ffffffff83bde4c8 (dpll_lock){+.+.}-{3:3}, at: dpll_lock_dumpit+0x13/0x20 > [52804.642747] > which lock already depends on the new lock. > > [...] Here is the summary with links: - [net,v2] dpll: fix possible deadlock during netlink dump operation https://git.kernel.org/netdev/net/c/53c0441dd2c4 You are awesome, thank you!
diff --git a/Documentation/netlink/specs/dpll.yaml b/Documentation/netlink/specs/dpll.yaml index b14aed18065f..3dcc9ece272a 100644 --- a/Documentation/netlink/specs/dpll.yaml +++ b/Documentation/netlink/specs/dpll.yaml @@ -384,8 +384,6 @@ operations: - type dump: - pre: dpll-lock-dumpit - post: dpll-unlock-dumpit reply: *dev-attrs - @@ -473,8 +471,6 @@ operations: - fractional-frequency-offset dump: - pre: dpll-lock-dumpit - post: dpll-unlock-dumpit request: attributes: - id diff --git a/drivers/dpll/dpll_netlink.c b/drivers/dpll/dpll_netlink.c index 314bb3775465..4ca9ad16cd95 100644 --- a/drivers/dpll/dpll_netlink.c +++ b/drivers/dpll/dpll_netlink.c @@ -1199,6 +1199,7 @@ int dpll_nl_pin_get_dumpit(struct sk_buff *skb, struct netlink_callback *cb) unsigned long i; int ret = 0; + mutex_lock(&dpll_lock); xa_for_each_marked_start(&dpll_pin_xa, i, pin, DPLL_REGISTERED, ctx->idx) { if (!dpll_pin_available(pin)) @@ -1218,6 +1219,8 @@ int dpll_nl_pin_get_dumpit(struct sk_buff *skb, struct netlink_callback *cb) } genlmsg_end(skb, hdr); } + mutex_unlock(&dpll_lock); + if (ret == -EMSGSIZE) { ctx->idx = i; return skb->len; @@ -1373,6 +1376,7 @@ int dpll_nl_device_get_dumpit(struct sk_buff *skb, struct netlink_callback *cb) unsigned long i; int ret = 0; + mutex_lock(&dpll_lock); xa_for_each_marked_start(&dpll_device_xa, i, dpll, DPLL_REGISTERED, ctx->idx) { hdr = genlmsg_put(skb, NETLINK_CB(cb->skb).portid, @@ -1389,6 +1393,8 @@ int dpll_nl_device_get_dumpit(struct sk_buff *skb, struct netlink_callback *cb) } genlmsg_end(skb, hdr); } + mutex_unlock(&dpll_lock); + if (ret == -EMSGSIZE) { ctx->idx = i; return skb->len; @@ -1439,20 +1445,6 @@ dpll_unlock_doit(const struct genl_split_ops *ops, struct sk_buff *skb, mutex_unlock(&dpll_lock); } -int dpll_lock_dumpit(struct netlink_callback *cb) -{ - mutex_lock(&dpll_lock); - - return 0; -} - -int dpll_unlock_dumpit(struct netlink_callback *cb) -{ - mutex_unlock(&dpll_lock); - - return 0; -} - int dpll_pin_pre_doit(const struct genl_split_ops *ops, struct sk_buff *skb, struct genl_info *info) { diff --git a/drivers/dpll/dpll_nl.c b/drivers/dpll/dpll_nl.c index eaee5be7aa64..1e95f5397cfc 100644 --- a/drivers/dpll/dpll_nl.c +++ b/drivers/dpll/dpll_nl.c @@ -95,9 +95,7 @@ static const struct genl_split_ops dpll_nl_ops[] = { }, { .cmd = DPLL_CMD_DEVICE_GET, - .start = dpll_lock_dumpit, .dumpit = dpll_nl_device_get_dumpit, - .done = dpll_unlock_dumpit, .flags = GENL_ADMIN_PERM | GENL_CMD_CAP_DUMP, }, { @@ -129,9 +127,7 @@ static const struct genl_split_ops dpll_nl_ops[] = { }, { .cmd = DPLL_CMD_PIN_GET, - .start = dpll_lock_dumpit, .dumpit = dpll_nl_pin_get_dumpit, - .done = dpll_unlock_dumpit, .policy = dpll_pin_get_dump_nl_policy, .maxattr = DPLL_A_PIN_ID, .flags = GENL_ADMIN_PERM | GENL_CMD_CAP_DUMP, diff --git a/drivers/dpll/dpll_nl.h b/drivers/dpll/dpll_nl.h index 92d4c9c4f788..f491262bee4f 100644 --- a/drivers/dpll/dpll_nl.h +++ b/drivers/dpll/dpll_nl.h @@ -30,8 +30,6 @@ dpll_post_doit(const struct genl_split_ops *ops, struct sk_buff *skb, void dpll_pin_post_doit(const struct genl_split_ops *ops, struct sk_buff *skb, struct genl_info *info); -int dpll_lock_dumpit(struct netlink_callback *cb); -int dpll_unlock_dumpit(struct netlink_callback *cb); int dpll_nl_device_id_get_doit(struct sk_buff *skb, struct genl_info *info); int dpll_nl_device_get_doit(struct sk_buff *skb, struct genl_info *info);