From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
To: linux-kernel@vger.kernel.org
Cc: Peter Zijlstra <peterz@infradead.org>,
Ingo Molnar <mingo@kernel.org>,
Steven Rostedt <rostedt@goodmis.org>,
Will Deacon <will@kernel.org>,
Thomas Gleixner <tglx@linutronix.de>,
"Paul E . McKenney" <paulmck@kernel.org>,
Linus Torvalds <torvalds@linux-foundation.org>,
Mike Galbraith <umgwanakikbuti@gmail.com>,
Minchan Kim <minchan@kernel.org>, Nitin Gupta <ngupta@vflare.org>,
Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>,
Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Subject: [PATCH 7/8] zram: Use local lock to protect per-CPU data
Date: Tue, 19 May 2020 22:19:11 +0200 [thread overview]
Message-ID: <20200519201912.1564477-8-bigeasy@linutronix.de> (raw)
In-Reply-To: <20200519201912.1564477-1-bigeasy@linutronix.de>
From: Mike Galbraith <umgwanakikbuti@gmail.com>
The zcomp driver uses per-CPU compression. The per-CPU data pointer is
acquired with get_cpu_ptr() which implicitly disables preemption.
It allocates memory inside the preempt disabled region which conflicts
with the PREEMPT_RT semantics.
Replace the implicit preemption control with an explicit local lock.
This allows RT kernels to substitute it with a real per CPU lock, which
serializes the access but keeps the code section preemptible. On non RT
kernels this maps to preempt_disable() as before, i.e. no functional
change.
[bigeasy: Use local_lock(), description, drop reordering]
Cc: Minchan Kim <minchan@kernel.org>
Cc: Nitin Gupta <ngupta@vflare.org>
Cc: Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>
Signed-off-by: Mike Galbraith <umgwanakikbuti@gmail.com>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
---
drivers/block/zram/zcomp.c | 8 ++++++--
1 file changed, 6 insertions(+), 2 deletions(-)
diff --git a/drivers/block/zram/zcomp.c b/drivers/block/zram/zcomp.c
index 1a8564a79d8dc..32854d460b299 100644
--- a/drivers/block/zram/zcomp.c
+++ b/drivers/block/zram/zcomp.c
@@ -11,6 +11,7 @@
#include <linux/sched.h>
#include <linux/cpu.h>
#include <linux/crypto.h>
+#include <linux/locallock.h>
#include "zcomp.h"
@@ -111,14 +112,17 @@ ssize_t zcomp_available_show(const char *comp, char *buf)
return sz;
}
+static DEFINE_LOCAL_LOCK(zcomp_lock);
+
struct zcomp_strm *zcomp_stream_get(struct zcomp *comp)
{
- return *get_cpu_ptr(comp->stream);
+ local_lock(zcomp_lock);
+ return *this_cpu_ptr(comp->stream);
}
void zcomp_stream_put(struct zcomp *comp)
{
- put_cpu_ptr(comp->stream);
+ local_unlock(zcomp_lock);
}
int zcomp_compress(struct zcomp_strm *zstrm,
--
2.26.2
next prev parent reply other threads:[~2020-05-19 20:20 UTC|newest]
Thread overview: 48+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-05-19 20:19 [PATCH 0/8] Introduce local_lock() Sebastian Andrzej Siewior
2020-05-19 20:19 ` [PATCH 1/8] locking: " Sebastian Andrzej Siewior
2020-05-20 12:04 ` Peter Zijlstra
2020-05-22 11:05 ` Sebastian Andrzej Siewior
2020-05-22 13:01 ` Peter Zijlstra
2020-05-19 20:19 ` [PATCH 2/8] radix-tree: Use local_lock for protection Sebastian Andrzej Siewior
2020-05-19 20:45 ` Matthew Wilcox
2020-05-19 20:54 ` Steven Rostedt
2020-05-20 2:05 ` Matthew Wilcox
2020-05-20 10:13 ` Sebastian Andrzej Siewior
2020-05-20 10:21 ` Peter Zijlstra
2020-05-20 12:28 ` Thomas Gleixner
2020-05-19 20:19 ` [PATCH 3/8] srcu: Use local_lock() for per-CPU struct srcu_data access Sebastian Andrzej Siewior
2020-05-20 10:24 ` Peter Zijlstra
2020-05-20 12:06 ` Sebastian Andrzej Siewior
2020-05-20 13:27 ` Peter Zijlstra
2020-05-20 17:42 ` Joel Fernandes
2020-05-20 18:28 ` Sebastian Andrzej Siewior
2020-05-20 18:35 ` Peter Zijlstra
2020-05-20 18:44 ` Joel Fernandes
2020-05-20 18:50 ` Uladzislau Rezki
2020-05-20 18:59 ` Joel Fernandes
2020-05-20 18:43 ` Paul E. McKenney
2020-05-22 15:12 ` Sebastian Andrzej Siewior
2020-05-22 17:39 ` Paul E. McKenney
2020-05-23 15:08 ` Sebastian Andrzej Siewior
2020-05-23 16:59 ` Paul E. McKenney
2020-05-24 19:03 ` Sebastian Andrzej Siewior
2020-05-25 3:27 ` Paul E. McKenney
2020-05-26 13:41 ` [PATCH] srcu: Avoid local_irq_save() before acquiring spinlock_t Sebastian Andrzej Siewior
2020-05-26 16:16 ` Paul E. McKenney
2020-05-26 16:31 ` Sebastian Andrzej Siewior
2020-05-19 20:19 ` [PATCH 4/8] mm/swap: Use local_lock for protection Sebastian Andrzej Siewior
2020-05-19 23:58 ` Andrew Morton
2020-05-20 2:17 ` Matthew Wilcox
2020-05-20 10:53 ` Peter Zijlstra
2020-05-19 20:19 ` [PATCH 5/8] squashfs: make use of local lock in multi_cpu decompressor Sebastian Andrzej Siewior
2020-05-20 10:56 ` Peter Zijlstra
2020-05-19 20:19 ` [PATCH 6/8] connector/cn_proc: Protect send_msg() with a local lock Sebastian Andrzej Siewior
2020-05-20 11:03 ` Peter Zijlstra
2020-05-19 20:19 ` Sebastian Andrzej Siewior [this message]
2020-05-20 11:07 ` [PATCH 7/8] zram: Use local lock to protect per-CPU data Peter Zijlstra
2020-05-19 20:19 ` [PATCH 8/8] mm/zswap: " Sebastian Andrzej Siewior
2020-05-19 21:46 ` Song Bao Hua
2020-05-20 10:26 ` Sebastian Andrzej Siewior
2020-05-20 11:13 ` Song Bao Hua
2020-05-20 11:57 ` Sebastian Andrzej Siewior
2020-05-20 12:01 ` Song Bao Hua
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