From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: linux-kernel@vger.kernel.org, stable@vger.kernel.org
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@kernel.org>,
"Peter Zijlstra (Intel)" <peterz@infradead.org>,
Lee Jones <lee.jones@linaro.org>
Subject: [PATCH 4.9 14/32] futex: Provide distinct return value when owner is exiting
Date: Tue, 2 Feb 2021 14:38:37 +0100 [thread overview]
Message-ID: <20210202132942.589673030@linuxfoundation.org> (raw)
In-Reply-To: <20210202132942.035179752@linuxfoundation.org>
From: Thomas Gleixner <tglx@linutronix.de>
commit ac31c7ff8624409ba3c4901df9237a616c187a5d upstream.
attach_to_pi_owner() returns -EAGAIN for various cases:
- Owner task is exiting
- Futex value has changed
The caller drops the held locks (hash bucket, mmap_sem) and retries the
operation. In case of the owner task exiting this can result in a live
lock.
As a preparatory step for seperating those cases, provide a distinct return
value (EBUSY) for the owner exiting case.
No functional change.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20191106224556.935606117@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
kernel/futex.c | 10 ++++++----
1 file changed, 6 insertions(+), 4 deletions(-)
--- a/kernel/futex.c
+++ b/kernel/futex.c
@@ -1918,12 +1918,13 @@ retry_private:
if (!ret)
goto retry;
goto out;
+ case -EBUSY:
case -EAGAIN:
/*
* Two reasons for this:
- * - Owner is exiting and we just wait for the
+ * - EBUSY: Owner is exiting and we just wait for the
* exit to complete.
- * - The user space value changed.
+ * - EAGAIN: The user space value changed.
*/
double_unlock_hb(hb1, hb2);
hb_waiters_dec(hb2);
@@ -2615,12 +2616,13 @@ retry_private:
goto out_unlock_put_key;
case -EFAULT:
goto uaddr_faulted;
+ case -EBUSY:
case -EAGAIN:
/*
* Two reasons for this:
- * - Task is exiting and we just wait for the
+ * - EBUSY: Task is exiting and we just wait for the
* exit to complete.
- * - The user space value changed.
+ * - EAGAIN: The user space value changed.
*/
queue_unlock(hb);
put_futex_key(&q.key);
next prev parent reply other threads:[~2021-02-02 14:19 UTC|newest]
Thread overview: 36+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-02-02 13:38 [PATCH 4.9 00/32] 4.9.255-rc1 review Greg Kroah-Hartman
2021-02-02 13:38 ` [PATCH 4.9 01/32] ACPI: sysfs: Prefer "compatible" modalias Greg Kroah-Hartman
2021-02-02 13:38 ` [PATCH 4.9 02/32] wext: fix NULL-ptr-dereference with cfg80211s lack of commit() Greg Kroah-Hartman
2021-02-02 13:38 ` [PATCH 4.9 03/32] net: usb: qmi_wwan: added support for Thales Cinterion PLSx3 modem family Greg Kroah-Hartman
2021-02-02 13:38 ` [PATCH 4.9 04/32] y2038: futex: Move compat implementation into futex.c Greg Kroah-Hartman
2021-02-02 13:38 ` [PATCH 4.9 05/32] futex: Move futex exit handling into futex code Greg Kroah-Hartman
2021-02-02 13:38 ` [PATCH 4.9 06/32] futex: Replace PF_EXITPIDONE with a state Greg Kroah-Hartman
2021-02-02 13:38 ` [PATCH 4.9 07/32] exit/exec: Seperate mm_release() Greg Kroah-Hartman
2021-02-02 13:38 ` [PATCH 4.9 08/32] futex: Split futex_mm_release() for exit/exec Greg Kroah-Hartman
2021-02-02 13:38 ` [PATCH 4.9 09/32] futex: Set task::futex_state to DEAD right after handling futex exit Greg Kroah-Hartman
2021-02-02 13:38 ` [PATCH 4.9 10/32] futex: Mark the begin of futex exit explicitly Greg Kroah-Hartman
2021-02-02 13:38 ` [PATCH 4.9 11/32] futex: Sanitize exit state handling Greg Kroah-Hartman
2021-02-02 13:38 ` [PATCH 4.9 12/32] futex: Provide state handling for exec() as well Greg Kroah-Hartman
2021-02-02 13:38 ` [PATCH 4.9 13/32] futex: Add mutex around futex exit Greg Kroah-Hartman
2021-02-02 13:38 ` Greg Kroah-Hartman [this message]
2021-02-02 13:38 ` [PATCH 4.9 15/32] futex: Prevent exit livelock Greg Kroah-Hartman
2021-02-02 13:38 ` [PATCH 4.9 16/32] KVM: x86/pmu: Fix HW_REF_CPU_CYCLES event pseudo-encoding in intel_arch_events[] Greg Kroah-Hartman
2021-02-02 13:38 ` [PATCH 4.9 17/32] KVM: x86: get smi pending status correctly Greg Kroah-Hartman
2021-02-02 13:38 ` [PATCH 4.9 18/32] leds: trigger: fix potential deadlock with libata Greg Kroah-Hartman
2021-02-02 13:38 ` [PATCH 4.9 19/32] mt7601u: fix kernel crash unplugging the device Greg Kroah-Hartman
2021-02-02 13:38 ` [PATCH 4.9 20/32] mt7601u: fix rx buffer refcounting Greg Kroah-Hartman
2021-02-02 13:38 ` [PATCH 4.9 21/32] ARM: imx: build suspend-imx6.S with arm instruction set Greg Kroah-Hartman
2021-02-02 13:38 ` [PATCH 4.9 22/32] netfilter: nft_dynset: add timeout extension to template Greg Kroah-Hartman
2021-02-02 13:38 ` [PATCH 4.9 23/32] xfrm: Fix oops in xfrm_replay_advance_bmp Greg Kroah-Hartman
2021-02-02 13:38 ` [PATCH 4.9 24/32] RDMA/cxgb4: Fix the reported max_recv_sge value Greg Kroah-Hartman
2021-02-02 13:38 ` [PATCH 4.9 25/32] iwlwifi: pcie: use jiffies for memory read spin time limit Greg Kroah-Hartman
2021-02-02 13:38 ` [PATCH 4.9 26/32] iwlwifi: pcie: reschedule in long-running memory reads Greg Kroah-Hartman
2021-02-02 13:38 ` [PATCH 4.9 27/32] mac80211: pause TX while changing interface type Greg Kroah-Hartman
2021-02-02 13:38 ` [PATCH 4.9 28/32] can: dev: prevent potential information leak in can_fill_info() Greg Kroah-Hartman
2021-02-02 13:38 ` [PATCH 4.9 29/32] iommu/vt-d: Gracefully handle DMAR units with no supported address widths Greg Kroah-Hartman
2021-02-02 13:38 ` [PATCH 4.9 30/32] iommu/vt-d: Dont dereference iommu_device if IOMMU_API is not built Greg Kroah-Hartman
2021-02-02 13:38 ` [PATCH 4.9 31/32] NFC: fix resource leak when target index is invalid Greg Kroah-Hartman
2021-02-02 13:38 ` [PATCH 4.9 32/32] NFC: fix possible resource leak Greg Kroah-Hartman
2021-02-03 9:53 ` [PATCH 4.9 00/32] 4.9.255-rc1 review Naresh Kamboju
2021-02-03 15:42 ` Shuah Khan
2021-02-03 20:41 ` Guenter Roeck
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