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Answer unknown ioctl commands quietly with -ENOTTY #4

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Merged
JohnAmadis merged 1 commit into from
Sep 29, 2026
Merged

Answer unknown ioctl commands quietly with -ENOTTY #4

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5 changes: 4 additions & 1 deletion include/dmdma_types.h
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Original file line number Diff line number Diff line change
Expand Up @@ -196,7 +196,10 @@ typedef enum
*/
typedef enum
{
dmdma_ioctl_cmd_start_transfer = 1, /**< arg = const dmdma_transfer_config_t* - configure and start */
/* Private commands start at DMDRVI_IOCTL_CUSTOM_BASE (0x1000, dmdrvi_ioctl.h)
* so they never collide with the standard DMDRVI_IOCTL_* commands (network,
* block, monitor) that dmdevfs and other generic clients send to any node. */
dmdma_ioctl_cmd_start_transfer = 0x1000, /**< arg = const dmdma_transfer_config_t* - configure and start */
dmdma_ioctl_cmd_stop_transfer, /**< Abort a transfer in progress; arg = NULL */
dmdma_ioctl_cmd_is_busy, /**< arg = bool* - whether a transfer is currently in flight */
dmdma_ioctl_cmd_get_remaining, /**< arg = size_t* - elements left in the current/last transfer */
Expand Down
15 changes: 11 additions & 4 deletions src/dmdma.c
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Original file line number Diff line number Diff line change
Expand Up @@ -11,6 +11,11 @@
/* "DMDA" packed into a uint32_t - see dmdrvi context magic-field convention */
#define DMDMA_CONTEXT_MAGIC 0x444D4441UL

#ifdef DMDRVI_IOCTL_CUSTOM_BASE
_Static_assert(dmdma_ioctl_cmd_start_transfer == DMDRVI_IOCTL_CUSTOM_BASE,
"dmdma private ioctl commands must start at DMDRVI_IOCTL_CUSTOM_BASE");
#endif

/* Generous upper bound on physical DMA controllers a board can have - real
* hardware (STM32F4/F7) has at most 2. */
#define DMDMA_MAX_CONTROLLERS 4U
Expand Down Expand Up @@ -655,10 +660,12 @@ dmod_dmdrvi_dif_api_declaration(2.0, dmdma, int, _ioctl,
return -EINVAL;
}

if (command < 0 || command >= dmdma_ioctl_cmd_max)
/* Not an error: generic clients (e.g. dmdevfs probing every node for the
* block/monitor classes) send standard DMDRVI_IOCTL_* commands a DMA stream
* does not implement - answer -ENOTTY quietly, as dmdrvi expects. */
if (command < dmdma_ioctl_cmd_start_transfer || command >= dmdma_ioctl_cmd_max)
{
DMOD_LOG_ERROR("Invalid ioctl command %d\n", command);
return -EINVAL;
return -ENOTTY;
}

dmdma_controller_t controller = context->config.controller;
Expand Down Expand Up @@ -713,7 +720,7 @@ dmod_dmdrvi_dif_api_declaration(2.0, dmdma, int, _ioctl,
return 0;

default:
return -EINVAL;
return -ENOTTY;
}
}

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