From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: linux-kernel@vger.kernel.org
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
stable@vger.kernel.org, Wonmin Jung <wonmin.jung@lge.com>,
Chanho Min <chanho.min@lge.com>, Takashi Iwai <tiwai@suse.de>
Subject: [PATCH 4.9 26/51] ALSA: pcm: Fix starvation on down_write_nonblock()
Date: Tue, 11 Dec 2018 16:41:34 +0100 [thread overview]
Message-ID: <20181211151616.165759966@linuxfoundation.org> (raw)
In-Reply-To: <20181211151612.328911565@linuxfoundation.org>
4.9-stable review patch. If anyone has any objections, please let me know.
------------------
From: Chanho Min <chanho.min@lge.com>
commit b888a5f713e4d17faaaff24316585a4eb07f35b7 upstream.
Commit 67ec1072b053 ("ALSA: pcm: Fix rwsem deadlock for non-atomic PCM
stream") fixes deadlock for non-atomic PCM stream. But, This patch
causes antother stuck.
If writer is RT thread and reader is a normal thread, the reader
thread will be difficult to get scheduled. It may not give chance to
release readlocks and writer gets stuck for a long time if they are
pinned to single cpu.
The deadlock described in the previous commit is because the linux
rwsem queues like a FIFO. So, we might need non-FIFO writelock, not
non-block one.
My suggestion is that the writer gives reader a chance to be scheduled
by using the minimum msleep() instaed of spinning without blocking by
writer. Also, The *_nonblock may be changed to *_nonfifo appropriately
to this concept.
In terms of performance, when trylock is failed, this minimum periodic
msleep will have the same performance as the tick-based
schedule()/wake_up_q().
[ Although this has a fairly high performance penalty, the relevant
code path became already rare due to the previous commit ("ALSA:
pcm: Call snd_pcm_unlink() conditionally at closing"). That is, now
this unconditional msleep appears only when using linked streams,
and this must be a rare case. So we accept this as a quick
workaround until finding a more suitable one -- tiwai ]
Fixes: 67ec1072b053 ("ALSA: pcm: Fix rwsem deadlock for non-atomic PCM stream")
Suggested-by: Wonmin Jung <wonmin.jung@lge.com>
Signed-off-by: Chanho Min <chanho.min@lge.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
sound/core/pcm_native.c | 11 ++++++-----
1 file changed, 6 insertions(+), 5 deletions(-)
--- a/sound/core/pcm_native.c
+++ b/sound/core/pcm_native.c
@@ -35,6 +35,7 @@
#include <sound/timer.h>
#include <sound/minors.h>
#include <linux/uio.h>
+#include <linux/delay.h>
/*
* Compatibility
@@ -78,12 +79,12 @@ static DECLARE_RWSEM(snd_pcm_link_rwsem)
* and this may lead to a deadlock when the code path takes read sem
* twice (e.g. one in snd_pcm_action_nonatomic() and another in
* snd_pcm_stream_lock()). As a (suboptimal) workaround, let writer to
- * spin until it gets the lock.
+ * sleep until all the readers are completed without blocking by writer.
*/
-static inline void down_write_nonblock(struct rw_semaphore *lock)
+static inline void down_write_nonfifo(struct rw_semaphore *lock)
{
while (!down_write_trylock(lock))
- cond_resched();
+ msleep(1);
}
/**
@@ -1825,7 +1826,7 @@ static int snd_pcm_link(struct snd_pcm_s
res = -ENOMEM;
goto _nolock;
}
- down_write_nonblock(&snd_pcm_link_rwsem);
+ down_write_nonfifo(&snd_pcm_link_rwsem);
write_lock_irq(&snd_pcm_link_rwlock);
if (substream->runtime->status->state == SNDRV_PCM_STATE_OPEN ||
substream->runtime->status->state != substream1->runtime->status->state ||
@@ -1872,7 +1873,7 @@ static int snd_pcm_unlink(struct snd_pcm
struct snd_pcm_substream *s;
int res = 0;
- down_write_nonblock(&snd_pcm_link_rwsem);
+ down_write_nonfifo(&snd_pcm_link_rwsem);
write_lock_irq(&snd_pcm_link_rwlock);
if (!snd_pcm_stream_linked(substream)) {
res = -EALREADY;
next prev parent reply other threads:[~2018-12-11 15:50 UTC|newest]
Thread overview: 56+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-12-11 15:41 [PATCH 4.9 00/51] 4.9.145-stable review Greg Kroah-Hartman
2018-12-11 15:41 ` [PATCH 4.9 01/51] media: omap3isp: Unregister media device as first Greg Kroah-Hartman
2018-12-11 15:41 ` [PATCH 4.9 02/51] iommu/vt-d: Fix NULL pointer dereference in prq_event_thread() Greg Kroah-Hartman
2018-12-11 15:41 ` [PATCH 4.9 03/51] brcmutil: really fix decoding channel info for 160 MHz bandwidth Greg Kroah-Hartman
2018-12-11 15:41 ` [PATCH 4.9 04/51] iommu/ipmmu-vmsa: Fix crash on early domain free Greg Kroah-Hartman
2018-12-11 15:41 ` [PATCH 4.9 05/51] can: rcar_can: Fix erroneous registration Greg Kroah-Hartman
2018-12-11 15:41 ` [PATCH 4.9 06/51] HID: input: Ignore battery reported by Symbol DS4308 Greg Kroah-Hartman
2018-12-11 15:41 ` [PATCH 4.9 07/51] batman-adv: Expand merged fragment buffer for full packet Greg Kroah-Hartman
2018-12-11 15:41 ` [PATCH 4.9 08/51] bnx2x: Assign unique DMAE channel number for FW DMAE transactions Greg Kroah-Hartman
2018-12-11 15:41 ` [PATCH 4.9 09/51] qed: Fix PTT leak in qed_drain() Greg Kroah-Hartman
2018-12-11 15:41 ` [PATCH 4.9 10/51] qed: Fix reading wrong value in loop condition Greg Kroah-Hartman
2018-12-11 15:41 ` [PATCH 4.9 11/51] net/mlx4_core: Zero out lkey field in SW2HW_MPT fw command Greg Kroah-Hartman
2018-12-11 15:41 ` [PATCH 4.9 12/51] net/mlx4_core: Fix uninitialized variable compilation warning Greg Kroah-Hartman
2018-12-11 15:41 ` [PATCH 4.9 13/51] net/mlx4: Fix UBSAN warning of signed integer overflow Greg Kroah-Hartman
2018-12-11 15:41 ` [PATCH 4.9 14/51] mtd: rawnand: qcom: Namespace prefix some commands Greg Kroah-Hartman
2018-12-11 15:41 ` [PATCH 4.9 15/51] net: faraday: ftmac100: remove netif_running(netdev) check before disabling interrupts Greg Kroah-Hartman
2018-12-11 15:41 ` [PATCH 4.9 16/51] iommu/vt-d: Use memunmap to free memremap Greg Kroah-Hartman
2018-12-11 15:41 ` [PATCH 4.9 17/51] team: no need to do team_notify_peers or team_mcast_rejoin when disabling port Greg Kroah-Hartman
2018-12-11 15:41 ` [PATCH 4.9 18/51] net: amd: add missing of_node_put() Greg Kroah-Hartman
2018-12-11 15:41 ` [PATCH 4.9 19/51] mm: dont warn about allocations which stall for too long Greg Kroah-Hartman
2018-12-11 15:41 ` [PATCH 4.9 20/51] ARC: [zebu] Remove CONFIG_INITRAMFS_SOURCE from defconfigs Greg Kroah-Hartman
2018-12-11 15:41 ` [PATCH 4.9 21/51] usb: quirk: add no-LPM quirk on SanDisk Ultra Flair device Greg Kroah-Hartman
2018-12-11 15:41 ` [PATCH 4.9 22/51] usb: appledisplay: Add 27" Apple Cinema Display Greg Kroah-Hartman
2018-12-11 15:41 ` [PATCH 4.9 23/51] USB: check usb_get_extra_descriptor for proper size Greg Kroah-Hartman
2018-12-11 15:41 ` [PATCH 4.9 24/51] ALSA: usb-audio: Fix UAF decrement if card has no live interfaces in card.c Greg Kroah-Hartman
2018-12-11 15:41 ` [PATCH 4.9 25/51] ALSA: hda: Add support for AMD Stoney Ridge Greg Kroah-Hartman
2018-12-11 15:41 ` Greg Kroah-Hartman [this message]
2018-12-11 15:41 ` [PATCH 4.9 27/51] ALSA: pcm: Call snd_pcm_unlink() conditionally at closing Greg Kroah-Hartman
2018-12-11 15:41 ` [PATCH 4.9 28/51] ALSA: pcm: Fix interval evaluation with openmin/max Greg Kroah-Hartman
2018-12-11 15:41 ` [PATCH 4.9 29/51] ALSA: hda/realtek - Fix speaker output regression on Thinkpad T570 Greg Kroah-Hartman
2018-12-11 15:41 ` [PATCH 4.9 30/51] virtio/s390: avoid race on vcdev->config Greg Kroah-Hartman
2018-12-11 15:41 ` [PATCH 4.9 31/51] virtio/s390: fix race in ccw_io_helper() Greg Kroah-Hartman
2018-12-11 15:41 ` [PATCH 4.9 32/51] SUNRPC: Fix leak of krb5p encode pages Greg Kroah-Hartman
2018-12-11 15:41 ` [PATCH 4.9 33/51] dmaengine: cppi41: delete channel from pending list when stop channel Greg Kroah-Hartman
2018-12-11 15:41 ` [PATCH 4.9 34/51] xhci: Prevent U1/U2 link pm states if exit latency is too long Greg Kroah-Hartman
2018-12-11 15:41 ` [PATCH 4.9 35/51] sr: pass down correctly sized SCSI sense buffer Greg Kroah-Hartman
2018-12-11 15:41 ` [PATCH 4.9 36/51] swiotlb: clean up reporting Greg Kroah-Hartman
2018-12-11 15:41 ` [PATCH 4.9 37/51] vsock: lookup and setup guest_cid inside vhost_vsock_lock Greg Kroah-Hartman
2018-12-11 15:41 ` [PATCH 4.9 38/51] vhost/vsock: fix use-after-free in network stack callers Greg Kroah-Hartman
2018-12-11 15:41 ` [PATCH 4.9 39/51] Staging: lustre: remove two build warnings Greg Kroah-Hartman
2018-12-11 15:41 ` [PATCH 4.9 40/51] cifs: Fix separator when building path from dentry Greg Kroah-Hartman
2018-12-11 15:41 ` [PATCH 4.9 41/51] staging: rtl8712: Fix possible buffer overrun Greg Kroah-Hartman
2018-12-11 15:41 ` [PATCH 4.9 42/51] tty: serial: 8250_mtk: always resume the device in probe Greg Kroah-Hartman
2018-12-11 15:41 ` [PATCH 4.9 43/51] tty: do not set TTY_IO_ERROR flag if console port Greg Kroah-Hartman
2018-12-11 15:41 ` [PATCH 4.9 44/51] kgdboc: fix KASAN global-out-of-bounds bug in param_set_kgdboc_var() Greg Kroah-Hartman
2018-12-11 15:41 ` [PATCH 4.9 45/51] mac80211_hwsim: Timer should be initialized before device registered Greg Kroah-Hartman
2018-12-11 15:41 ` [PATCH 4.9 46/51] mac80211: Clear beacon_int in ieee80211_do_stop Greg Kroah-Hartman
2018-12-11 15:41 ` [PATCH 4.9 47/51] mac80211: ignore tx status for PS stations in ieee80211_tx_status_ext Greg Kroah-Hartman
2018-12-11 15:41 ` [PATCH 4.9 48/51] mac80211: fix reordering of buffered broadcast packets Greg Kroah-Hartman
2018-12-11 15:41 ` [PATCH 4.9 49/51] mac80211: ignore NullFunc frames in the duplicate detection Greg Kroah-Hartman
2018-12-11 15:41 ` [PATCH 4.9 50/51] kbuild: fix linker feature test macros when cross compiling with Clang Greg Kroah-Hartman
2018-12-11 15:41 ` [PATCH 4.9 51/51] kbuild: allow to use GCC toolchain not in Clang search path Greg Kroah-Hartman
2018-12-11 20:33 ` [PATCH 4.9 00/51] 4.9.145-stable review kernelci.org bot
2018-12-11 23:57 ` shuah
2018-12-12 6:45 ` Naresh Kamboju
2018-12-12 18:49 ` Guenter Roeck
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