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TASK_CURRENT_SYSCALL(9) Machine State TASK_CURRENT_SYSCALL(9)

NAME

task_current_syscall - Discover what a blocked task is doing.

SYNOPSIS

int task_current_syscall(struct task_struct * target, long * callno, unsigned long args[6], unsigned int maxargs, unsigned long * sp, unsigned long * pc);

ARGUMENTS

target

thread to examine

callno

filled with system call number or -1

args[6]

filled with maxargs system call arguments

maxargs

number of elements in args to fill

sp

filled with user stack pointer

pc

filled with user PC

DESCRIPTION

If target is blocked in a system call, returns zero with *callno set to the the call´s number and args filled in with its arguments. Registers not used for system call arguments may not be available and it is not kosher to use struct user_regset calls while the system call is still in progress. Note we may get this result if target has finished its system call but not yet returned to user mode, such as when it´s stopped for signal handling or syscall exit tracing.

If target is blocked in the kernel during a fault or exception, returns zero with *callno set to -1 and does not fill in args. If so, it´s now safe to examine target using struct user_regset get calls as long as we´re sure target won´t return to user mode.

Returns -EAGAIN if target does not remain blocked.

Returns -EINVAL if maxargs is too large (maximum is six).

May 2024 Kernel Hackers Manual 2.6.