New patch at end....
Boaz Harrosh wrote:
> On Tue, Mar 18 2008 at 18:52 +0200, Michael Reed <mdr@xxxxxxx> wrote:
>> Boaz Harrosh wrote:
>>> On Tue, Mar 18 2008 at 18:12 +0200, Michael Reed <mdr@xxxxxxx> wrote:
>>>> Michael Reed wrote:
>>>>> Boaz Harrosh wrote:
>>>>> <snip>
>>>>>>>> Just to demonstrate what I mean a patch is attached. Just as an RFC, totally
>>>>>>>> untested.
>>>>>>> I can try this out and see what happens.
>>>>>>>
>>>>>>>
>>>>>> Will not compile here is a cleaner one
>>>>> Still in my queue. Hopefully I'll get to poke at this today.
>>>> Patch compiles cleanly and appears to have no effect on the misc.
>>>> sg_* commands I've executed including sg_dd, sg_inq, sg_luns, sg_readcap.
>>>>
>>>> Mike
>>>>
>>>>> Mike
>>>>>
>>> <patch sniped>
>>>
>>> If you remove the original fix to sg.c
>>> ([PATCH] 2.6.25-rc4-git3 - inquiry cmd issued via /dev/sg? device causes infinite loop in 2.6.24)
>>>
>>> and apply this patch, does it solve your original infinite loop?
>> Unfortunately, the infinite loop only occurred at 2.6.24. I'll see if
>> I can break the current rc by removing some known fixes.
>>
>> Care to gen a patch for 2.6.24?
>>
>> Mike
>>
>>> Thanks
>>> Boaz
>>>
>
> here is the same principle on Linux 2.6.24
> ---
> [PATCH] scsi: Always complete BLOCK_PC commands
>
> Current code, in some IO combinations could wrongly retry
> a BLOCK_PC command in chunks. This was never intended.
> Fix it that BLOCK_PC will always complete atomically
>
> Signed-off-by: Boaz Harrosh <bharrosh@xxxxxxxxxxx>
> ---
> git-diff --stat -p
> drivers/scsi/scsi_lib.c | 9 +++++++++
> 1 files changed, 9 insertions(+), 0 deletions(-)
>
> diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
> index a9ac5b1..ae32012 100644
> --- a/drivers/scsi/scsi_lib.c
> +++ b/drivers/scsi/scsi_lib.c
> @@ -966,7 +966,16 @@ void scsi_io_completion(struct scsi_cmnd *cmd, unsigned int good_bytes)
> req->sense_len = len;
> }
> }
> + good_bytes = req->data_len;
> req->data_len = cmd->resid;
> +retry_end_req:
> + if (scsi_end_request(cmd, 1, good_bytes, 0) != NULL) {
> + WARN_ON(1);
> + good_bytes = req->data_len;
> + goto retry_end_req;
> + }
> +
> + return;
> }
>
> /*
I applied the patch to 2.6.24 and here's the result. It first completes 255 bytes,
then repeatedly completes 56 bytes until it's all completed. This seems rather cumbersome.
And points out that the rounding in sg_build_indirect() needs to be fixed.
scsi_execute_async: inquiry buf length 255, use_sg 1, bio e0000170820fae00, bi_size 512
mptscsih_qcmd: cmd e0000170b06e1980 / 18, dd 2, sg_count 1, sglist e0000170b340e900, bufflen 255, bi_size 512
scsi_io_completion: e0000170b06e1980: inquiry completion: result 0, good_bytes 255, bufflen 255, sense_valid 0, sense e0000170b34ac5c0 / 0
WARNING: at drivers/scsi/scsi_lib.c:1025 scsi_io_completion()
Call Trace:
[<a000000100013ac0>] show_stack+0x40/0xa0
sp=e0000170821c79b0 bsp=e0000170821c1050
[<a000000100013b50>] dump_stack+0x30/0x60
sp=e0000170821c7b80 bsp=e0000170821c1038
[<a0000001005628b0>] scsi_io_completion+0x350/0x980
sp=e0000170821c7b80 bsp=e0000170821c0fd0
[<a0000001005547b0>] scsi_finish_command+0x1d0/0x200
sp=e0000170821c7ba0 bsp=e0000170821c0fa0
[<a000000100564070>] scsi_softirq_done+0x270/0x2a0
sp=e0000170821c7ba0 bsp=e0000170821c0f70
[<a0000001003a8480>] blk_done_softirq+0x140/0x1a0
sp=e0000170821c7bb0 bsp=e0000170821c0f58
[<a0000001000b6eb0>] __do_softirq+0xf0/0x240
sp=e0000170821c7bc0 bsp=e0000170821c0ee0
[<a0000001000b7070>] do_softirq+0x70/0xc0
sp=e0000170821c7bc0 bsp=e0000170821c0e80
[<a0000001000b7360>] irq_exit+0x80/0xa0
sp=e0000170821c7bc0 bsp=e0000170821c0e68
[<a000000100011250>] ia64_handle_irq+0x2f0/0x320
sp=e0000170821c7bc0 bsp=e0000170821c0e38
[<a00000010000b100>] ia64_leave_kernel+0x0/0x270
sp=e0000170821c7bc0 bsp=e0000170821c0e38
[<a000000100014bf0>] default_idle+0x110/0x180
sp=e0000170821c7d90 bsp=e0000170821c0df0
[<a000000100013870>] cpu_idle+0x230/0x360
sp=e0000170821c7e30 bsp=e0000170821c0db0
[<a000000100961910>] start_secondary+0x4d0/0x500
sp=e0000170821c7e30 bsp=e0000170821c0d70
[<a0000001007619c0>] __kprobes_text_end+0x340/0x370
sp=e0000170821c7e30 bsp=e0000170821c0d70
scsi_io_completion: e0000170b06e1980: inquiry completion: result 0, good_bytes 56, bufflen 255, sense_valid 0, sense e0000170b34ac5c0 / 0
WARNING: at drivers/scsi/scsi_lib.c:1025 scsi_io_completion()
Call Trace:
[<a000000100013ac0>] show_stack+0x40/0xa0
sp=e0000170821c79b0 bsp=e0000170821c1050
[<a000000100013b50>] dump_stack+0x30/0x60
sp=e0000170821c7b80 bsp=e0000170821c1038
[<a0000001005628b0>] scsi_io_completion+0x350/0x980
sp=e0000170821c7b80 bsp=e0000170821c0fd0
[<a0000001005547b0>] scsi_finish_command+0x1d0/0x200
sp=e0000170821c7ba0 bsp=e0000170821c0fa0
[<a000000100564070>] scsi_softirq_done+0x270/0x2a0
sp=e0000170821c7ba0 bsp=e0000170821c0f70
[<a0000001003a8480>] blk_done_softirq+0x140/0x1a0
sp=e0000170821c7bb0 bsp=e0000170821c0f58
[<a0000001000b6eb0>] __do_softirq+0xf0/0x240
sp=e0000170821c7bc0 bsp=e0000170821c0ee0
[<a0000001000b7070>] do_softirq+0x70/0xc0
sp=e0000170821c7bc0 bsp=e0000170821c0e80
[<a0000001000b7360>] irq_exit+0x80/0xa0
sp=e0000170821c7bc0 bsp=e0000170821c0e68
[<a000000100011250>] ia64_handle_irq+0x2f0/0x320
sp=e0000170821c7bc0 bsp=e0000170821c0e38
[<a00000010000b100>] ia64_leave_kernel+0x0/0x270
sp=e0000170821c7bc0 bsp=e0000170821c0e38
[<a000000100014bf0>] default_idle+0x110/0x180
sp=e0000170821c7d90 bsp=e0000170821c0df0
[<a000000100013870>] cpu_idle+0x230/0x360
sp=e0000170821c7e30 bsp=e0000170821c0db0
[<a000000100961910>] start_secondary+0x4d0/0x500
sp=e0000170821c7e30 bsp=e0000170821c0d70
[<a0000001007619c0>] __kprobes_text_end+0x340/0x370
sp=e0000170821c7e30 bsp=e0000170821c0d70
scsi_io_completion: e0000170b06e1980: inquiry completion: result 0, good_bytes 56, bufflen 255, sense_valid 0, sense e0000170b34ac5c0 / 0
WARNING: at drivers/scsi/scsi_lib.c:1025 scsi_io_completion()
Call Trace:
[<a000000100013ac0>] show_stack+0x40/0xa0
sp=e0000170821c79b0 bsp=e0000170821c1050
[<a000000100013b50>] dump_stack+0x30/0x60
sp=e0000170821c7b80 bsp=e0000170821c1038
[<a0000001005628b0>] scsi_io_completion+0x350/0x980
sp=e0000170821c7b80 bsp=e0000170821c0fd0
[<a0000001005547b0>] scsi_finish_command+0x1d0/0x200
sp=e0000170821c7ba0 bsp=e0000170821c0fa0
[<a000000100564070>] scsi_softirq_done+0x270/0x2a0
sp=e0000170821c7ba0 bsp=e0000170821c0f70
[<a0000001003a8480>] blk_done_softirq+0x140/0x1a0
sp=e0000170821c7bb0 bsp=e0000170821c0f58
[<a0000001000b6eb0>] __do_softirq+0xf0/0x240
sp=e0000170821c7bc0 bsp=e0000170821c0ee0
[<a0000001000b7070>] do_softirq+0x70/0xc0
sp=e0000170821c7bc0 bsp=e0000170821c0e80
[<a0000001000b7360>] irq_exit+0x80/0xa0
sp=e0000170821c7bc0 bsp=e0000170821c0e68
[<a000000100011250>] ia64_handle_irq+0x2f0/0x320
sp=e0000170821c7bc0 bsp=e0000170821c0e38
[<a00000010000b100>] ia64_leave_kernel+0x0/0x270
sp=e0000170821c7bc0 bsp=e0000170821c0e38
[<a000000100014bf0>] default_idle+0x110/0x180
sp=e0000170821c7d90 bsp=e0000170821c0df0
[<a000000100013870>] cpu_idle+0x230/0x360
sp=e0000170821c7e30 bsp=e0000170821c0db0
[<a000000100961910>] start_secondary+0x4d0/0x500
sp=e0000170821c7e30 bsp=e0000170821c0d70
[<a0000001007619c0>] __kprobes_text_end+0x340/0x370
sp=e0000170821c7e30 bsp=e0000170821c0d70
scsi_io_completion: e0000170b06e1980: inquiry completion: result 0, good_bytes 56, bufflen 255, sense_valid 0, sense e0000170b34ac5c0 / 0
WARNING: at drivers/scsi/scsi_lib.c:1025 scsi_io_completion()
Call Trace:
[<a000000100013ac0>] show_stack+0x40/0xa0
sp=e0000170821c79b0 bsp=e0000170821c1050
[<a000000100013b50>] dump_stack+0x30/0x60
sp=e0000170821c7b80 bsp=e0000170821c1038
[<a0000001005628b0>] scsi_io_completion+0x350/0x980
sp=e0000170821c7b80 bsp=e0000170821c0fd0
[<a0000001005547b0>] scsi_finish_command+0x1d0/0x200
sp=e0000170821c7ba0 bsp=e0000170821c0fa0
[<a000000100564070>] scsi_softirq_done+0x270/0x2a0
sp=e0000170821c7ba0 bsp=e0000170821c0f70
[<a0000001003a8480>] blk_done_softirq+0x140/0x1a0
sp=e0000170821c7bb0 bsp=e0000170821c0f58
[<a0000001000b6eb0>] __do_softirq+0xf0/0x240
sp=e0000170821c7bc0 bsp=e0000170821c0ee0
[<a0000001000b7070>] do_softirq+0x70/0xc0
sp=e0000170821c7bc0 bsp=e0000170821c0e80
[<a0000001000b7360>] irq_exit+0x80/0xa0
sp=e0000170821c7bc0 bsp=e0000170821c0e68
[<a000000100011250>] ia64_handle_irq+0x2f0/0x320
sp=e0000170821c7bc0 bsp=e0000170821c0e38
[<a00000010000b100>] ia64_leave_kernel+0x0/0x270
sp=e0000170821c7bc0 bsp=e0000170821c0e38
[<a000000100014bf0>] default_idle+0x110/0x180
sp=e0000170821c7d90 bsp=e0000170821c0df0
[<a000000100013870>] cpu_idle+0x230/0x360
sp=e0000170821c7e30 bsp=e0000170821c0db0
[<a000000100961910>] start_secondary+0x4d0/0x500
sp=e0000170821c7e30 bsp=e0000170821c0d70
[<a0000001007619c0>] __kprobes_text_end+0x340/0x370
sp=e0000170821c7e30 bsp=e0000170821c0d70
scsi_io_completion: e0000170b06e1980: inquiry completion: result 0, good_bytes 56, bufflen 255, sense_valid 0, sense e0000170b34ac5c0 / 0
WARNING: at drivers/scsi/scsi_lib.c:1025 scsi_io_completion()
Call Trace:
[<a000000100013ac0>] show_stack+0x40/0xa0
sp=e0000170821c79b0 bsp=e0000170821c1050
[<a000000100013b50>] dump_stack+0x30/0x60
sp=e0000170821c7b80 bsp=e0000170821c1038
[<a0000001005628b0>] scsi_io_completion+0x350/0x980
sp=e0000170821c7b80 bsp=e0000170821c0fd0
[<a0000001005547b0>] scsi_finish_command+0x1d0/0x200
sp=e0000170821c7ba0 bsp=e0000170821c0fa0
[<a000000100564070>] scsi_softirq_done+0x270/0x2a0
sp=e0000170821c7ba0 bsp=e0000170821c0f70
[<a0000001003a8480>] blk_done_softirq+0x140/0x1a0
sp=e0000170821c7bb0 bsp=e0000170821c0f58
[<a0000001000b6eb0>] __do_softirq+0xf0/0x240
sp=e0000170821c7bc0 bsp=e0000170821c0ee0
[<a0000001000b7070>] do_softirq+0x70/0xc0
sp=e0000170821c7bc0 bsp=e0000170821c0e80
[<a0000001000b7360>] irq_exit+0x80/0xa0
sp=e0000170821c7bc0 bsp=e0000170821c0e68
[<a000000100011250>] ia64_handle_irq+0x2f0/0x320
sp=e0000170821c7bc0 bsp=e0000170821c0e38
[<a00000010000b100>] ia64_leave_kernel+0x0/0x270
sp=e0000170821c7bc0 bsp=e0000170821c0e38
[<a000000100014bf0>] default_idle+0x110/0x180
sp=e0000170821c7d90 bsp=e0000170821c0df0
[<a000000100013870>] cpu_idle+0x230/0x360
sp=e0000170821c7e30 bsp=e0000170821c0db0
[<a000000100961910>] start_secondary+0x4d0/0x500
sp=e0000170821c7e30 bsp=e0000170821c0d70
[<a0000001007619c0>] __kprobes_text_end+0x340/0x370
sp=e0000170821c7e30 bsp=e0000170821c0d70
scsi_io_completion: e0000170b06e1980: inquiry completion: result 0, good_bytes 56, bufflen 255, sense_valid 0, sense e0000170b34ac5c0 / 0
How 'bout this instead? It completes what finished and then
ends the request. I think. I tried it using 2.6.24 and got
no infinite loop.
--- kdbu/drivers/scsi/scsi_lib.c 2008-01-24 14:58:37.000000000 -0800
+++ kdb/drivers/scsi/scsi_lib.c 2008-03-19 08:49:19.456568385 -0700
@@ -657,13 +657,12 @@ static struct scsi_cmnd *scsi_end_reques
/*
* If there are blocks left over at the end, set up the command
* to queue the remainder of them.
+ * blk_pc_requests are never requeued.
*/
- if (end_that_request_chunk(req, uptodate, bytes)) {
+ if (end_that_request_chunk(req, uptodate, bytes) &&
+ !blk_pc_request(req)) {
int leftover = (req->hard_nr_sectors << 9);
- if (blk_pc_request(req))
- leftover = req->data_len;
-
/* kill remainder if no retrys */
if (!uptodate && blk_noretry_request(req))
end_that_request_chunk(req, 0, leftover);
Signed-off-by: Michael Reed <mdr@xxxxxxx>
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