[ 029/149] usb: fsl_udc_core: Fix scheduling while atomic dump message

From: Greg KH
Date: Fri Mar 30 2012 - 18:31:09 EST

3.2-stable review patch. If anyone has any objections, please let me know.


From: Peter Chen <peter.chen@xxxxxxxxxxxxx>

commit c5cc5ed86667d4ae74fe40ee4ed893f4b46aba05 upstream.

When loading g_ether gadget, there is below message:

[<80012248>] (dump_backtrace+0x0/0x10c) from [<803cb42c>] (dump_stack+0x18/0x1c)
r7:00000000 r6:80512000 r5:8052bef8 r4:80513f30
[<803cb414>] (dump_stack+0x0/0x1c) from [<8000feb4>] (show_regs+0x44/0x50)
[<8000fe70>] (show_regs+0x0/0x50) from [<8004c840>] (__schedule_bug+0x68/0x84)
r5:8052bef8 r4:80513f30
[<8004c7d8>] (__schedule_bug+0x0/0x84) from [<803cd0e4>] (__schedule+0x4b0/0x528)
r5:8052bef8 r4:809aad00
[<803ccc34>] (__schedule+0x0/0x528) from [<803cd214>] (_cond_resched+0x44/0x58)
[<803cd1d0>] (_cond_resched+0x0/0x58) from [<800a9488>] (dma_pool_alloc+0x184/0x250)
r5:9f9b4000 r4:9fb4fb80
[<800a9304>] (dma_pool_alloc+0x0/0x250) from [<802a8ad8>] (fsl_req_to_dtd+0xac/0x180)
[<802a8a2c>] (fsl_req_to_dtd+0x0/0x180) from [<802a8ce4>] (fsl_ep_queue+0x138/0x274)
[<802a8bac>] (fsl_ep_queue+0x0/0x274) from [<7f004328>] (composite_setup+0x2d4/0xfac [g_ether])
[<7f004054>] (composite_setup+0x0/0xfac [g_ether]) from [<802a9bb4>] (fsl_udc_irq+0x8dc/0xd38)
[<802a92d8>] (fsl_udc_irq+0x0/0xd38) from [<800704f8>] (handle_irq_event_percpu+0x54/0x188)
[<800704a4>] (handle_irq_event_percpu+0x0/0x188) from [<80070674>] (handle_irq_event+0x48/0x68)
[<8007062c>] (handle_irq_event+0x0/0x68) from [<800738ec>] (handle_level_irq+0xb4/0x138)
r5:80514f94 r4:80514f40
[<80073838>] (handle_level_irq+0x0/0x138) from [<8006ffa4>] (generic_handle_irq+0x38/0x44)
r7:00000012 r6:80510b1c r5:80529860 r4:80512000
[<8006ff6c>] (generic_handle_irq+0x0/0x44) from [<8000f4c4>] (handle_IRQ+0x54/0xb4)
[<8000f470>] (handle_IRQ+0x0/0xb4) from [<800085b8>] (tzic_handle_irq+0x64/0x94)
r9:412fc085 r8:00000000 r7:80513f30 r6:00000001 r5:00000000
[<80008554>] (tzic_handle_irq+0x0/0x94) from [<8000e680>] (__irq_svc+0x40/0x60)

The reason of above dump message is calling dma_poll_alloc with can-schedule
mem_flags at atomic context.

To fix this problem, below changes are made:
- fsl_req_to_dtd doesn't need to be protected by spin_lock_irqsave,
as struct usb_request can be access at process context. Move lock
to beginning of hardware visit (fsl_queue_td).
- Change the memory flag which using to allocate dTD descriptor buffer,
the memory flag can be from gadget layer.

It is tested at i.mx51 bbg board with g_mass_storage, g_ether, g_serial.

Signed-off-by: Peter Chen <peter.chen@xxxxxxxxxxxxx>
Acked-by: Li Yang <leoli@xxxxxxxxxxxxx>
Signed-off-by: Felipe Balbi <balbi@xxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

drivers/usb/gadget/fsl_udc_core.c | 18 ++++++++----------
1 file changed, 8 insertions(+), 10 deletions(-)

--- a/drivers/usb/gadget/fsl_udc_core.c
+++ b/drivers/usb/gadget/fsl_udc_core.c
@@ -768,7 +768,7 @@ static void fsl_queue_td(struct fsl_ep *
* @is_last: return flag if it is the last dTD of the request
* return: pointer to the built dTD */
static struct ep_td_struct *fsl_build_dtd(struct fsl_req *req, unsigned *length,
- dma_addr_t *dma, int *is_last)
+ dma_addr_t *dma, int *is_last, gfp_t gfp_flags)
u32 swap_temp;
struct ep_td_struct *dtd;
@@ -777,7 +777,7 @@ static struct ep_td_struct *fsl_build_dt
*length = min(req->req.length - req->req.actual,

- dtd = dma_pool_alloc(udc_controller->td_pool, GFP_KERNEL, dma);
+ dtd = dma_pool_alloc(udc_controller->td_pool, gfp_flags, dma);
if (dtd == NULL)
return dtd;

@@ -827,7 +827,7 @@ static struct ep_td_struct *fsl_build_dt

/* Generate dtd chain for a request */
-static int fsl_req_to_dtd(struct fsl_req *req)
+static int fsl_req_to_dtd(struct fsl_req *req, gfp_t gfp_flags)
unsigned count;
int is_last;
@@ -836,7 +836,7 @@ static int fsl_req_to_dtd(struct fsl_req
dma_addr_t dma;

do {
- dtd = fsl_build_dtd(req, &count, &dma, &is_last);
+ dtd = fsl_build_dtd(req, &count, &dma, &is_last, gfp_flags);
if (dtd == NULL)
return -ENOMEM;

@@ -910,13 +910,11 @@ fsl_ep_queue(struct usb_ep *_ep, struct
req->req.actual = 0;
req->dtd_count = 0;

- spin_lock_irqsave(&udc->lock, flags);
/* build dtds and push them to device queue */
- if (!fsl_req_to_dtd(req)) {
+ if (!fsl_req_to_dtd(req, gfp_flags)) {
+ spin_lock_irqsave(&udc->lock, flags);
fsl_queue_td(ep, req);
} else {
- spin_unlock_irqrestore(&udc->lock, flags);
return -ENOMEM;

@@ -1295,7 +1293,7 @@ static int ep0_prime_status(struct fsl_u
ep_is_in(ep) ? DMA_TO_DEVICE : DMA_FROM_DEVICE);
req->mapped = 1;

- if (fsl_req_to_dtd(req) == 0)
+ if (fsl_req_to_dtd(req, GFP_ATOMIC) == 0)
fsl_queue_td(ep, req);
return -ENOMEM;
@@ -1379,7 +1377,7 @@ static void ch9getstatus(struct fsl_udc
req->mapped = 1;

/* prime the data phase */
- if ((fsl_req_to_dtd(req) == 0))
+ if ((fsl_req_to_dtd(req, GFP_ATOMIC) == 0))
fsl_queue_td(ep, req);
else /* no mem */
goto stall;

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