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Subject[PATCH RT 17/22] crypto: scompress - serialize RT percpu scratch buffer access with a local lock
4.14.63-rt41-rc1 stable review patch.
If anyone has any objections, please let me know.

------------------

From: Mike Galbraith <efault@gmx.de>

[ Upstream commit 1a4eff3f8e743d149be26a414822710aef07fe14 ]

| BUG: sleeping function called from invalid context at kernel/locking/rtmutex.c:974
| in_atomic(): 1, irqs_disabled(): 0, pid: 1401, name: cryptomgr_test
| Preemption disabled at:
| [<ffff00000849941c>] scomp_acomp_comp_decomp+0x34/0x1a0
| CPU: 21 PID: 1401 Comm: cryptomgr_test Tainted: G W 4.16.18-rt9-rt #1
| Hardware name: www.cavium.com crb-1s/crb-1s, BIOS 0.3 Apr 25 2017
| Call trace:
| dump_backtrace+0x0/0x1c8
| show_stack+0x24/0x30
| dump_stack+0xac/0xe8
| ___might_sleep+0x124/0x188
| rt_spin_lock+0x40/0x88
| zip_load_instr+0x44/0x170 [thunderx_zip]
| zip_deflate+0x184/0x378 [thunderx_zip]
| zip_compress+0xb0/0x130 [thunderx_zip]
| zip_scomp_compress+0x48/0x60 [thunderx_zip]
| scomp_acomp_comp_decomp+0xd8/0x1a0
| scomp_acomp_compress+0x24/0x30
| test_acomp+0x15c/0x558
| alg_test_comp+0xc0/0x128
| alg_test.part.6+0x120/0x2c0
| alg_test+0x6c/0xa0
| cryptomgr_test+0x50/0x58
| kthread+0x134/0x138
| ret_from_fork+0x10/0x18

Mainline disables preemption to serialize percpu scratch buffer access,
causing the splat above. Serialize with a local lock for RT instead.

Signed-off-by: Mike Galbraith <efault@gmx.de>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
---
crypto/scompress.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/crypto/scompress.c b/crypto/scompress.c
index 2075e2c4e7df..c6b4e265c6bf 100644
--- a/crypto/scompress.c
+++ b/crypto/scompress.c
@@ -24,6 +24,7 @@
#include <linux/cryptouser.h>
#include <net/netlink.h>
#include <linux/scatterlist.h>
+#include <linux/locallock.h>
#include <crypto/scatterwalk.h>
#include <crypto/internal/acompress.h>
#include <crypto/internal/scompress.h>
@@ -34,6 +35,7 @@ static void * __percpu *scomp_src_scratches;
static void * __percpu *scomp_dst_scratches;
static int scomp_scratch_users;
static DEFINE_MUTEX(scomp_lock);
+static DEFINE_LOCAL_IRQ_LOCK(scomp_scratches_lock);

#ifdef CONFIG_NET
static int crypto_scomp_report(struct sk_buff *skb, struct crypto_alg *alg)
@@ -193,7 +195,7 @@ static int scomp_acomp_comp_decomp(struct acomp_req *req, int dir)
void **tfm_ctx = acomp_tfm_ctx(tfm);
struct crypto_scomp *scomp = *tfm_ctx;
void **ctx = acomp_request_ctx(req);
- const int cpu = get_cpu();
+ const int cpu = local_lock_cpu(scomp_scratches_lock);
u8 *scratch_src = *per_cpu_ptr(scomp_src_scratches, cpu);
u8 *scratch_dst = *per_cpu_ptr(scomp_dst_scratches, cpu);
int ret;
@@ -228,7 +230,7 @@ static int scomp_acomp_comp_decomp(struct acomp_req *req, int dir)
1);
}
out:
- put_cpu();
+ local_unlock_cpu(scomp_scratches_lock);
return ret;
}

--
2.18.0

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