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dmaengine: at_xdmac: lock fixes
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Using _bh variant for spin locks causes this kind of warning:
Starting logging: ------------[ cut here ]------------
WARNING: CPU: 0 PID: 3 at /ssd_drive/linux/kernel/softirq.c:151
__local_bh_enable_ip+0xe8/0xf4()
Modules linked in:
CPU: 0 PID: 3 Comm: ksoftirqd/0 Not tainted 4.1.0-rc2+ torvalds#94
Hardware name: Atmel SAMA5
[<c0013c04>] (unwind_backtrace) from [<c00118a4>] (show_stack+0x10/0x14)
[<c00118a4>] (show_stack) from [<c001bbcc>]
(warn_slowpath_common+0x80/0xac)
[<c001bbcc>] (warn_slowpath_common) from [<c001bc14>]
(warn_slowpath_null+0x1c/0x24)
[<c001bc14>] (warn_slowpath_null) from [<c001e28c>]
(__local_bh_enable_ip+0xe8/0xf4)
[<c001e28c>] (__local_bh_enable_ip) from [<c01fdbd0>]
(at_xdmac_device_terminate_all+0xf4/0x100)
[<c01fdbd0>] (at_xdmac_device_terminate_all) from [<c02221a4>]
(atmel_complete_tx_dma+0x34/0xf4)
[<c02221a4>] (atmel_complete_tx_dma) from [<c01fe4ac>]
(at_xdmac_tasklet+0x14c/0x1ac)
[<c01fe4ac>] (at_xdmac_tasklet) from [<c001de58>]
(tasklet_action+0x68/0xb4)
[<c001de58>] (tasklet_action) from [<c001dfdc>]
(__do_softirq+0xfc/0x238)
[<c001dfdc>] (__do_softirq) from [<c001e140>] (run_ksoftirqd+0x28/0x34)
[<c001e140>] (run_ksoftirqd) from [<c0033a3c>]
(smpboot_thread_fn+0x138/0x18c)
[<c0033a3c>] (smpboot_thread_fn) from [<c0030e7c>] (kthread+0xdc/0xf0)
[<c0030e7c>] (kthread) from [<c000f480>] (ret_from_fork+0x14/0x34)
---[ end trace b57b14a99c1d8812 ]---

It comes from the fact that devices can called some code from the DMA
controller with irq disabled. _bh variant is not intended to be used in
this case since it can enable irqs. Switch to irqsave/irqrestore variant to
avoid this situation.

Signed-off-by: Ludovic Desroches <ludovic.desroches@atmel.com>
Cc: stable@vger.kernel.org # 4.0 and later
  • Loading branch information
@ldesroches
ldesroches authored and Nicolas Ferre committed Jun 8, 2015
1 parent 9aa3498 commit e3801c9
Showing 1 changed file with 45 additions and 32 deletions.
77 changes: 45 additions & 32 deletions drivers/dma/at_xdmac.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -415,8 +415,9 @@ static dma_cookie_t at_xdmac_tx_submit(struct dma_async_tx_descriptor *tx)
struct at_xdmac_desc *desc = txd_to_at_desc(tx);
struct at_xdmac_chan *atchan = to_at_xdmac_chan(tx->chan);
dma_cookie_t cookie;
unsigned long irqflags;

spin_lock_bh(&atchan->lock);
spin_lock_irqsave(&atchan->lock, irqflags);
cookie = dma_cookie_assign(tx);

dev_vdbg(chan2dev(tx->chan), "%s: atchan 0x%p, add desc 0x%p to xfers_list\n",
Expand All @@ -425,7 +426,7 @@ static dma_cookie_t at_xdmac_tx_submit(struct dma_async_tx_descriptor *tx)
if (list_is_singular(&atchan->xfers_list))
at_xdmac_start_xfer(atchan, desc);

spin_unlock_bh(&atchan->lock);
spin_unlock_irqrestore(&atchan->lock, irqflags);
return cookie;
}

Expand Down Expand Up @@ -563,6 +564,8 @@ at_xdmac_prep_slave_sg(struct dma_chan *chan, struct scatterlist *sgl,
struct scatterlist *sg;
int i;
unsigned int xfer_size = 0;
unsigned long irqflags;
struct dma_async_tx_descriptor *ret = NULL;

if (!sgl)
return NULL;
Expand All @@ -578,7 +581,7 @@ at_xdmac_prep_slave_sg(struct dma_chan *chan, struct scatterlist *sgl,
flags);

/* Protect dma_sconfig field that can be modified by set_slave_conf. */
spin_lock_bh(&atchan->lock);
spin_lock_irqsave(&atchan->lock, irqflags);

/* Prepare descriptors. */
for_each_sg(sgl, sg, sg_len, i) {
Expand All @@ -589,8 +592,7 @@ at_xdmac_prep_slave_sg(struct dma_chan *chan, struct scatterlist *sgl,
mem = sg_dma_address(sg);
if (unlikely(!len)) {
dev_err(chan2dev(chan), "sg data length is zero\n");
spin_unlock_bh(&atchan->lock);
return NULL;
goto spin_unlock;
}
dev_dbg(chan2dev(chan), "%s: * sg%d len=%u, mem=0x%08x\n",
__func__, i, len, mem);
Expand All @@ -600,8 +602,7 @@ at_xdmac_prep_slave_sg(struct dma_chan *chan, struct scatterlist *sgl,
dev_err(chan2dev(chan), "can't get descriptor\n");
if (first)
list_splice_init(&first->descs_list, &atchan->free_descs_list);
spin_unlock_bh(&atchan->lock);
return NULL;
goto spin_unlock;
}

/* Linked list descriptor setup. */
Expand Down Expand Up @@ -645,13 +646,15 @@ at_xdmac_prep_slave_sg(struct dma_chan *chan, struct scatterlist *sgl,
xfer_size += len;
}

spin_unlock_bh(&atchan->lock);

first->tx_dma_desc.flags = flags;
first->xfer_size = xfer_size;
first->direction = direction;
ret = &first->tx_dma_desc;

return &first->tx_dma_desc;
spin_unlock:
spin_unlock_irqrestore(&atchan->lock, irqflags);
return ret;
}

static struct dma_async_tx_descriptor *
Expand All @@ -664,6 +667,7 @@ at_xdmac_prep_dma_cyclic(struct dma_chan *chan, dma_addr_t buf_addr,
struct at_xdmac_desc *first = NULL, *prev = NULL;
unsigned int periods = buf_len / period_len;
int i;
unsigned long irqflags;
u32 cfg;

dev_dbg(chan2dev(chan), "%s: buf_addr=%pad, buf_len=%zd, period_len=%zd, dir=%s, flags=0x%lx\n",
Expand All @@ -683,16 +687,16 @@ at_xdmac_prep_dma_cyclic(struct dma_chan *chan, dma_addr_t buf_addr,
for (i = 0; i < periods; i++) {
struct at_xdmac_desc *desc = NULL;

spin_lock_bh(&atchan->lock);
spin_lock_irqsave(&atchan->lock, irqflags);
desc = at_xdmac_get_desc(atchan);
if (!desc) {
dev_err(chan2dev(chan), "can't get descriptor\n");
if (first)
list_splice_init(&first->descs_list, &atchan->free_descs_list);
spin_unlock_bh(&atchan->lock);
spin_unlock_irqrestore(&atchan->lock, irqflags);
return NULL;
}
spin_unlock_bh(&atchan->lock);
spin_unlock_irqrestore(&atchan->lock, irqflags);
dev_dbg(chan2dev(chan),
"%s: desc=0x%p, tx_dma_desc.phys=%pad\n",
__func__, desc, &desc->tx_dma_desc.phys);
Expand Down Expand Up @@ -767,6 +771,7 @@ at_xdmac_prep_dma_memcpy(struct dma_chan *chan, dma_addr_t dest, dma_addr_t src,
| AT_XDMAC_CC_SIF(0)
| AT_XDMAC_CC_MBSIZE_SIXTEEN
| AT_XDMAC_CC_TYPE_MEM_TRAN;
unsigned long irqflags;

dev_dbg(chan2dev(chan), "%s: src=%pad, dest=%pad, len=%zd, flags=0x%lx\n",
__func__, &src, &dest, len, flags);
Expand Down Expand Up @@ -799,9 +804,9 @@ at_xdmac_prep_dma_memcpy(struct dma_chan *chan, dma_addr_t dest, dma_addr_t src,

dev_dbg(chan2dev(chan), "%s: remaining_size=%zu\n", __func__, remaining_size);

spin_lock_bh(&atchan->lock);
spin_lock_irqsave(&atchan->lock, irqflags);
desc = at_xdmac_get_desc(atchan);
spin_unlock_bh(&atchan->lock);
spin_unlock_irqrestore(&atchan->lock, irqflags);
if (!desc) {
dev_err(chan2dev(chan), "can't get descriptor\n");
if (first)
Expand Down Expand Up @@ -887,6 +892,7 @@ at_xdmac_tx_status(struct dma_chan *chan, dma_cookie_t cookie,
int residue;
u32 cur_nda, mask, value;
u8 dwidth = 0;
unsigned long flags;

ret = dma_cookie_status(chan, cookie, txstate);
if (ret == DMA_COMPLETE)
Expand All @@ -895,7 +901,7 @@ at_xdmac_tx_status(struct dma_chan *chan, dma_cookie_t cookie,
if (!txstate)
return ret;

spin_lock_bh(&atchan->lock);
spin_lock_irqsave(&atchan->lock, flags);

desc = list_first_entry(&atchan->xfers_list, struct at_xdmac_desc, xfer_node);

Expand All @@ -905,8 +911,7 @@ at_xdmac_tx_status(struct dma_chan *chan, dma_cookie_t cookie,
*/
if (!desc->active_xfer) {
dma_set_residue(txstate, desc->xfer_size);
spin_unlock_bh(&atchan->lock);
return ret;
goto spin_unlock;
}

residue = desc->xfer_size;
Expand Down Expand Up @@ -937,14 +942,14 @@ at_xdmac_tx_status(struct dma_chan *chan, dma_cookie_t cookie,
}
residue += at_xdmac_chan_read(atchan, AT_XDMAC_CUBC) << dwidth;

spin_unlock_bh(&atchan->lock);

dma_set_residue(txstate, residue);

dev_dbg(chan2dev(chan),
"%s: desc=0x%p, tx_dma_desc.phys=%pad, tx_status=%d, cookie=%d, residue=%d\n",
__func__, desc, &desc->tx_dma_desc.phys, ret, cookie, residue);

spin_unlock:
spin_unlock_irqrestore(&atchan->lock, flags);
return ret;
}

Expand All @@ -965,8 +970,9 @@ static void at_xdmac_remove_xfer(struct at_xdmac_chan *atchan,
static void at_xdmac_advance_work(struct at_xdmac_chan *atchan)
{
struct at_xdmac_desc *desc;
unsigned long flags;

spin_lock_bh(&atchan->lock);
spin_lock_irqsave(&atchan->lock, flags);

/*
* If channel is enabled, do nothing, advance_work will be triggered
Expand All @@ -981,7 +987,7 @@ static void at_xdmac_advance_work(struct at_xdmac_chan *atchan)
at_xdmac_start_xfer(atchan, desc);
}

spin_unlock_bh(&atchan->lock);
spin_unlock_irqrestore(&atchan->lock, flags);
}

static void at_xdmac_handle_cyclic(struct at_xdmac_chan *atchan)
Expand Down Expand Up @@ -1117,12 +1123,13 @@ static int at_xdmac_device_config(struct dma_chan *chan,
{
struct at_xdmac_chan *atchan = to_at_xdmac_chan(chan);
int ret;
unsigned long flags;

dev_dbg(chan2dev(chan), "%s\n", __func__);

spin_lock_bh(&atchan->lock);
spin_lock_irqsave(&atchan->lock, flags);
ret = at_xdmac_set_slave_config(chan, config);
spin_unlock_bh(&atchan->lock);
spin_unlock_irqrestore(&atchan->lock, flags);

return ret;
}
Expand All @@ -1131,18 +1138,19 @@ static int at_xdmac_device_pause(struct dma_chan *chan)
{
struct at_xdmac_chan *atchan = to_at_xdmac_chan(chan);
struct at_xdmac *atxdmac = to_at_xdmac(atchan->chan.device);
unsigned long flags;

dev_dbg(chan2dev(chan), "%s\n", __func__);

if (test_and_set_bit(AT_XDMAC_CHAN_IS_PAUSED, &atchan->status))
return 0;

spin_lock_bh(&atchan->lock);
spin_lock_irqsave(&atchan->lock, flags);
at_xdmac_write(atxdmac, AT_XDMAC_GRWS, atchan->mask);
while (at_xdmac_chan_read(atchan, AT_XDMAC_CC)
& (AT_XDMAC_CC_WRIP | AT_XDMAC_CC_RDIP))
cpu_relax();
spin_unlock_bh(&atchan->lock);
spin_unlock_irqrestore(&atchan->lock, flags);

return 0;
}
Expand All @@ -1151,16 +1159,19 @@ static int at_xdmac_device_resume(struct dma_chan *chan)
{
struct at_xdmac_chan *atchan = to_at_xdmac_chan(chan);
struct at_xdmac *atxdmac = to_at_xdmac(atchan->chan.device);
unsigned long flags;

dev_dbg(chan2dev(chan), "%s\n", __func__);

spin_lock_bh(&atchan->lock);
if (!at_xdmac_chan_is_paused(atchan))
spin_lock_irqsave(&atchan->lock, flags);
if (!at_xdmac_chan_is_paused(atchan)) {
spin_unlock_irqrestore(&atchan->lock, flags);
return 0;
}

at_xdmac_write(atxdmac, AT_XDMAC_GRWR, atchan->mask);
clear_bit(AT_XDMAC_CHAN_IS_PAUSED, &atchan->status);
spin_unlock_bh(&atchan->lock);
spin_unlock_irqrestore(&atchan->lock, flags);

return 0;
}
Expand All @@ -1170,10 +1181,11 @@ static int at_xdmac_device_terminate_all(struct dma_chan *chan)
struct at_xdmac_desc *desc, *_desc;
struct at_xdmac_chan *atchan = to_at_xdmac_chan(chan);
struct at_xdmac *atxdmac = to_at_xdmac(atchan->chan.device);
unsigned long flags;

dev_dbg(chan2dev(chan), "%s\n", __func__);

spin_lock_bh(&atchan->lock);
spin_lock_irqsave(&atchan->lock, flags);
at_xdmac_write(atxdmac, AT_XDMAC_GD, atchan->mask);
while (at_xdmac_read(atxdmac, AT_XDMAC_GS) & atchan->mask)
cpu_relax();
Expand All @@ -1183,7 +1195,7 @@ static int at_xdmac_device_terminate_all(struct dma_chan *chan)
at_xdmac_remove_xfer(atchan, desc);

clear_bit(AT_XDMAC_CHAN_IS_CYCLIC, &atchan->status);
spin_unlock_bh(&atchan->lock);
spin_unlock_irqrestore(&atchan->lock, flags);

return 0;
}
Expand All @@ -1193,8 +1205,9 @@ static int at_xdmac_alloc_chan_resources(struct dma_chan *chan)
struct at_xdmac_chan *atchan = to_at_xdmac_chan(chan);
struct at_xdmac_desc *desc;
int i;
unsigned long flags;

spin_lock_bh(&atchan->lock);
spin_lock_irqsave(&atchan->lock, flags);

if (at_xdmac_chan_is_enabled(atchan)) {
dev_err(chan2dev(chan),
Expand Down Expand Up @@ -1225,7 +1238,7 @@ static int at_xdmac_alloc_chan_resources(struct dma_chan *chan)
dev_dbg(chan2dev(chan), "%s: allocated %d descriptors\n", __func__, i);

spin_unlock:
spin_unlock_bh(&atchan->lock);
spin_unlock_irqrestore(&atchan->lock, flags);
return i;
}

Expand Down

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