ENOCSI
Linux / POSIXERRORCriticalDeviceHIGH confidence
No CSI Structure Available
Production Risk
Rare; STREAMS-specific resource exhaustion.
What this means
ENOCSI (errno 50) is a Linux/STREAMS-specific error returned when no Channel Service Interface (CSI) structure is available.
Why it happens
- 1STREAMS driver unable to allocate a CSI structure
How to reproduce
STREAMS driver CSI allocation failure.
trigger — this will error
trigger — this will error
// errno = ENOCSI when STREAMS CSI unavailable
expected output
No CSI structure available (ENOCSI)
Fix
Free STREAMS resources and retry
WHEN When ENOCSI is returned
Free STREAMS resources and retry
// Release other STREAMS resources to free CSI structures close(other_streams_fd); // Then retry the operation
Why this works
CSI structures are a limited kernel resource; releasing other STREAMS connections frees them.
Sources
Official documentation ↗
Linux Programmer Manual errno(3)
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