[PATCH v2] async_tx: use the channel-switch Kconfig symbol

[PATCH v2] async_tx: use the channel-switch Kconfig symbol

[Pengpeng Hou]

ASYNC_TX_ENABLE_CHANNEL_SWITCH is the Kconfig symbol selected by DMA
engine providers that need async_tx channel switching.

CONFIG_ASYNC_TX_CHANNEL_SWITCH is not generated by Kconfig, so the
shortcut in async_tx.h tests an impossible symbol. Use the generated
CONFIG_ASYNC_TX_ENABLE_CHANNEL_SWITCH name instead.

Fixes: b802c8410ca9 ("async_tx: deprecate broken support for channel switching")
Assisted-by: Codex:gpt-5
Signed-off-by: Pengpeng Hou <pengpeng@iscas.ac.cn>
---
Changes since v1: https://lore.kernel.org/all/20260624081404.82604-1-pengpeng@iscas.ac.cn/
- rebase on current async_tx sources
- document that only ASYNC_TX_ENABLE_CHANNEL_SWITCH is generated by Kconfig

The Kconfig name and preprocessor path were reviewed statically; no DMA-
engine runtime test was performed.

 include/linux/async_tx.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/include/linux/async_tx.h b/include/linux/async_tx.h
index 1ca9f9e05f4f..1659a06c034b 100644
--- a/include/linux/async_tx.h
+++ b/include/linux/async_tx.h
@@ -74,7 +74,7 @@ struct async_submit_ctl {
 	void *scribble;
 };
 
-#if defined(CONFIG_DMA_ENGINE) && !defined(CONFIG_ASYNC_TX_CHANNEL_SWITCH)
+#if defined(CONFIG_DMA_ENGINE) && !defined(CONFIG_ASYNC_TX_ENABLE_CHANNEL_SWITCH)
 #define async_tx_issue_pending_all dma_issue_pending_all
 
 /**
-- 
2.50.1 (Apple Git-155)

Re: [PATCH v2] async_tx: use the channel-switch Kconfig symbol

[kernel test robot]

:::::: 
:::::: Manual check reason: "linux-review patch is more than 7 days old, verify it wasn't already superseded"
:::::: 

BCC: lkp@intel.com
CC: oe-kbuild-all@lists.linux.dev
In-Reply-To: <20260814075403.13950-1-pengpeng@iscas.ac.cn>
References: <20260814075403.13950-1-pengpeng@iscas.ac.cn>
TO: Pengpeng Hou <pengpeng@iscas.ac.cn>
CC: linux-kernel@vger.kernel.org
CC: Pengpeng Hou <pengpeng@iscas.ac.cn>

Hi Pengpeng,

kernel test robot noticed the following build warnings:

[auto build test WARNING on linus/master]
[also build test WARNING on v7.2 next-20260821]
[cannot apply to linux-review/Pengpeng-Hou/async_tx-Use-the-channel-switch-Kconfig-symbol/20260807-091006]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]

url:    https://github.com/intel-lab-lkp/linux/commits/Pengpeng-Hou/async_tx-use-the-channel-switch-Kconfig-symbol/20260814-155403
base:   linus/master
patch link:    https://lore.kernel.org/r/20260814075403.13950-1-pengpeng%40iscas.ac.cn
patch subject: [PATCH v2] async_tx: use the channel-switch Kconfig symbol
:::::: branch date: 15 hours ago
:::::: commit date: 15 hours ago
config: sparc64-randconfig-r053-20260823 (https://download.01.org/0day-ci/archive/20260823/202608230650.oZ4LyTZ0-lkp@intel.com/config)
compiler: clang version 24.0.0git (https://github.com/llvm/llvm-project 935bfc708590c60147a79c7df145bb6e68b1d388)
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20260823/202608230650.oZ4LyTZ0-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/r/202608230650.oZ4LyTZ0-lkp@intel.com/

All warnings (new ones prefixed by >>):

>> crypto/async_tx/async_tx.c:43:1: warning: no previous prototype for function '__async_tx_find_channel' [-Wmissing-prototypes]
      43 | __async_tx_find_channel(struct async_submit_ctl *submit,
         | ^
   crypto/async_tx/async_tx.c:42:1: note: declare 'static' if the function is not intended to be used outside of this translation unit
      42 | struct dma_chan *
         | ^
         | static 
   1 warning generated.


vim +/__async_tx_find_channel +43 crypto/async_tx/async_tx.c

af1f951eb6ef27b Dan Williams 2009-08-29  35  
9bc89cd82d6f88f Dan Williams 2007-01-02  36  /**
47437b2c9a64315 Dan Williams 2008-02-02  37   * __async_tx_find_channel - find a channel to carry out the operation or let
9bc89cd82d6f88f Dan Williams 2007-01-02  38   *	the transaction execute synchronously
a08abd8ca890a37 Dan Williams 2009-06-03  39   * @submit: transaction dependency and submission modifiers
9bc89cd82d6f88f Dan Williams 2007-01-02  40   * @tx_type: transaction type
9bc89cd82d6f88f Dan Williams 2007-01-02  41   */
9bc89cd82d6f88f Dan Williams 2007-01-02  42  struct dma_chan *
a08abd8ca890a37 Dan Williams 2009-06-03 @43  __async_tx_find_channel(struct async_submit_ctl *submit,
9bc89cd82d6f88f Dan Williams 2007-01-02  44  			enum dma_transaction_type tx_type)
9bc89cd82d6f88f Dan Williams 2007-01-02  45  {
a08abd8ca890a37 Dan Williams 2009-06-03  46  	struct dma_async_tx_descriptor *depend_tx = submit->depend_tx;
a08abd8ca890a37 Dan Williams 2009-06-03  47  
9bc89cd82d6f88f Dan Williams 2007-01-02  48  	/* see if we can keep the chain on one channel */
9bc89cd82d6f88f Dan Williams 2007-01-02  49  	if (depend_tx &&
9bc89cd82d6f88f Dan Williams 2007-01-02  50  	    dma_has_cap(tx_type, depend_tx->chan->device->cap_mask))
9bc89cd82d6f88f Dan Williams 2007-01-02  51  		return depend_tx->chan;
729b5d1b8ec72c2 Dan Williams 2009-03-25  52  	return async_dma_find_channel(tx_type);
9bc89cd82d6f88f Dan Williams 2007-01-02  53  }
47437b2c9a64315 Dan Williams 2008-02-02  54  EXPORT_SYMBOL_GPL(__async_tx_find_channel);
9bc89cd82d6f88f Dan Williams 2007-01-02  55  #endif
9bc89cd82d6f88f Dan Williams 2007-01-02  56  
19242d7233df7d6 Dan Williams 2008-04-17  57  

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