[PATCH net 0/2] Fix spinlock usage in HWBM

Hi,

these two patches fix spinlock related issues introduced in v4.6. They
have been reported by Russell King and Jean-Jacques Hiblot.

Thanks to them,

Gregory

Gregory CLEMENT (2):
  net: mvneta: Fix lacking spinlock initialization
  net: hwbm: Fix unbalanced spinlock in error case

 drivers/net/ethernet/marvell/mvneta_bm.c | 1 +
 net/core/hwbm.c                          | 3 +++
 2 files changed, 4 insertions(+)

-- 
2.5.0

The spinlock used by the hwbm functions must be initialized by the
network driver. This commit fixes this lack and the following erros when
lockdep is enabled:

INFO: trying to register non-static key.
the code is fine but needs lockdep annotation.
turning off the locking correctness validator.
[<c010ff80>] (unwind_backtrace) from [<c010bd08>] (show_stack+0x10/0x14)
[<c010bd08>] (show_stack) from [<c032913c>] (dump_stack+0xb4/0xe0)
[<c032913c>] (dump_stack) from [<c01670e4>] (__lock_acquire+0x1f58/0x2060)
[<c01670e4>] (__lock_acquire) from [<c0167dec>] (lock_acquire+0xa4/0xd0)
[<c0167dec>] (lock_acquire) from [<c06f6650>] (_raw_spin_lock_irqsave+0x54/0x68)
[<c06f6650>] (_raw_spin_lock_irqsave) from [<c058e830>] (hwbm_pool_add+0x1c/0xdc)
[<c058e830>] (hwbm_pool_add) from [<c043f4e8>] (mvneta_bm_pool_use+0x338/0x490)
[<c043f4e8>] (mvneta_bm_pool_use) from [<c0443198>] (mvneta_probe+0x654/0x1284)
[<c0443198>] (mvneta_probe) from [<c03b894c>] (platform_drv_probe+0x4c/0xb0)
[<c03b894c>] (platform_drv_probe) from [<c03b7158>] (driver_probe_device+0x214/0x2c0)
[<c03b7158>] (driver_probe_device) from [<c03b72c4>] (__driver_attach+0xc0/0xc4)
[<c03b72c4>] (__driver_attach) from [<c03b5440>] (bus_for_each_dev+0x68/0x9c)
[<c03b5440>] (bus_for_each_dev) from [<c03b65b8>] (bus_add_driver+0x1a0/0x218)
[<c03b65b8>] (bus_add_driver) from [<c03b79cc>] (driver_register+0x78/0xf8)
[<c03b79cc>] (driver_register) from [<c01018f4>] (do_one_initcall+0x90/0x1dc)
[<c01018f4>] (do_one_initcall) from [<c0900de4>] (kernel_init_freeable+0x15c/0x1fc)
[<c0900de4>] (kernel_init_freeable) from [<c06eed90>] (kernel_init+0x8/0x114)
[<c06eed90>] (kernel_init) from [<c0107910>] (ret_from_fork+0x14/0x24)

Fixes: baa11ebc0c76 ("net: mvneta: Use the new hwbm framework")
Reported-by: Russell King <redacted>
Cc: <redacted>
Signed-off-by: Gregory CLEMENT <redacted>
---
 drivers/net/ethernet/marvell/mvneta_bm.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/net/ethernet/marvell/mvneta_bm.c b/drivers/net/ethernet/marvell/mvneta_bm.c
index 01fccec632ec..466939f8f0cf 100644
--- a/drivers/net/ethernet/marvell/mvneta_bm.c
+++ b/drivers/net/ethernet/marvell/mvneta_bm.c

@@ -189,6 +189,7 @@ struct mvneta_bm_pool *mvneta_bm_pool_use(struct mvneta_bm *priv, u8 pool_id,
 			SKB_DATA_ALIGN(sizeof(struct skb_shared_info));
 		hwbm_pool->construct = mvneta_bm_construct;
 		hwbm_pool->priv = new_pool;
+		spin_lock_init(&hwbm_pool->lock);
 
 		/* Create new pool */
 		err = mvneta_bm_pool_create(priv, new_pool);

-- 
2.5.0

When hwbm_pool_add exited in error the spinlock was not released. This
patch fixes this issue.

Fixes: 8cb2d8bf57e6 ("net: add a hardware buffer management helper API")
Reported-by: Jean-Jacques Hiblot <redacted>
Cc: <redacted>
Signed-off-by: Gregory CLEMENT <redacted>
---
 net/core/hwbm.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/net/core/hwbm.c b/net/core/hwbm.c
index 941c28486896..2cab489ae62e 100644
--- a/net/core/hwbm.c
+++ b/net/core/hwbm.c

@@ -55,18 +55,21 @@ int hwbm_pool_add(struct hwbm_pool *bm_pool, unsigned int buf_num, gfp_t gfp)
 	spin_lock_irqsave(&bm_pool->lock, flags);
 	if (bm_pool->buf_num == bm_pool->size) {
 		pr_warn("pool already filled\n");
+		spin_unlock_irqrestore(&bm_pool->lock, flags);
 		return bm_pool->buf_num;
 	}
 
 	if (buf_num + bm_pool->buf_num > bm_pool->size) {
 		pr_warn("cannot allocate %d buffers for pool\n",
 			buf_num);
+		spin_unlock_irqrestore(&bm_pool->lock, flags);
 		return 0;
 	}
 
 	if ((buf_num + bm_pool->buf_num) < bm_pool->buf_num) {
 		pr_warn("Adding %d buffers to the %d current buffers will overflow\n",
 			buf_num,  bm_pool->buf_num);
+		spin_unlock_irqrestore(&bm_pool->lock, flags);
 		return 0;
 	}
 

-- 
2.5.0

From: Gregory CLEMENT <redacted>
Date: Tue, 24 May 2016 18:03:24 +0200

these two patches fix spinlock related issues introduced in v4.6. They
have been reported by Russell King and Jean-Jacques Hiblot.

Series applied and queued up for -stable.