trace_pid_next(9)

✨ trace_pid_next(9) ✨

okay so bestie, welcome to trace_pid_next(9) from the Kernel API Manual — this is the little function that does the "next" dance for kernel tracing pid lists 💅

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🌸 NAME 🌸

trace_pid_next — literally the function that's used for seq_file to get to the next pid of a pid_list 🎀

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🦋 SYNOPSIS 🦋

void * trace_pid_next (struct trace_pid_list *pid_list , void *v ,
       loff_t *pos );

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💖 ARGUMENTS 💖

• pid_list — the pid list to show 👑 this is the lineup you're scrolling through.
• v — the last pid that was shown. and bestie, listen: it's +1 the actual pid, and that whole +1 situation exists specifically so that a pid of zero can still be displayed. genius behavior fr fr.
• pos — the position of the file 📍

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🌈 DESCRIPTION 🌈

So this is what the seq_file "next" operation calls to iterate the pids listed in a trace_pid_list structure. that's the whole vibe ✨

It returns pid+1, because we want to be able to display a pid of zero — but NULL would stop the iteration 💀 so the +1 is doing the actual emotional labor here. iconic, honestly.

lowkey important: return NULL and the iteration just ends. no more pids for you 🙈

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🫶 SEE ALSO 🫶

Kernel file ./kernel/trace/trace_pid.c, plus all these besties:

• trace_find_filtered_pid(9)
• trace_ignore_this_task(9)
• trace_filter_add_remove_task(9)
• trace_pid_start(9)
• trace_pid_show(9)

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and that's the page! 🍓 sign-off time: this one's from the <pink>./kernel/trace</pink> source, dated <purple>October 2026</purple>, hanging out in the Kernel API Manual. go read your kernel source bestie, ily 💜🧚