From 4ece39c56cfdd5647d4061f3c084b9de6f9e443c Mon Sep 17 00:00:00 2001 From: Tom de Vries Date: Thu, 11 Jan 2024 10:12:48 +0100 Subject: [PATCH] [gdb/testsuite] Extend gdb.base/kill-during-detach.exp I ran into the following FAIL: ... (gdb) python kill_and_detach()^M Traceback (most recent call last):^M File "", line 1, in ^M File "", line 7, in kill_and_detach^M gdb.error: Selected thread is running.^M Error while executing Python code.^M (gdb) FAIL: gdb.base/kill-during-detach.exp: exit_p=true: checkpoint_p=true: \ python kill_and_detach() ... The FAIL happens as follows: - gdb is debugging a process A - a checkpoint is created, in other words, fork is called in the inferior, after which we have: - checkpoint 0 (the fork parent, process A), and - checkpoint 1 (the fork child, process B). - during checkpoint creation, lseek is called in the inferior (process A) for all file descriptors, and it returns != -1 for at least one file descriptor. - the process A continues in the background - gdb detaches, from process A - gdb switches to process B, in other words, it restarts checkpoint 1 - while restarting checkpoint 1, gdb tries to call lseek in the inferior (process B), but this fails because gdb incorrectly thinks that inferior B is running. This happens because linux_nat_switch_fork patches the pid of process B into the current inferior and current thread which where originally representing process A. So, because process A was running in the background, the thread_info fields executing and resumed are set accordingly, but they are not correct for process B. There's a line in fork_load_infrun_state that fixes up the thread_info field stop_pc, so fix this by adding similar fixups for the executing and resumed fields alongside. The FAIL did not always reproduce, so extend the test-case to reliably trigger this scenario. Tested on x86_64-linux. Approved-By: Kevin Buettner PR gdb/31203 Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=31203 --- gdb/linux-fork.c | 2 ++ gdb/testsuite/gdb.base/kill-during-detach.c | 28 +++++++++++++++++++ gdb/testsuite/gdb.base/kill-during-detach.exp | 16 ++++++++++- 3 files changed, 45 insertions(+), 1 deletion(-) diff --git a/gdb/linux-fork.c b/gdb/linux-fork.c index 64b83e79204..b531119d44a 100644 --- a/gdb/linux-fork.c +++ b/gdb/linux-fork.c @@ -227,6 +227,8 @@ fork_load_infrun_state (struct fork_info *fp) inferior_thread ()->set_stop_pc (regcache_read_pc (get_thread_regcache (inferior_thread ()))); + inferior_thread ()->set_executing (false); + inferior_thread ()->set_resumed (false); nullify_last_target_wait_ptid (); /* Now restore the file positions of open file descriptors. */ diff --git a/gdb/testsuite/gdb.base/kill-during-detach.c b/gdb/testsuite/gdb.base/kill-during-detach.c index 2d9cca91e2f..8ffb0456bfd 100644 --- a/gdb/testsuite/gdb.base/kill-during-detach.c +++ b/gdb/testsuite/gdb.base/kill-during-detach.c @@ -16,14 +16,42 @@ along with this program. If not, see . */ #include +#include +#include volatile int dont_exit_just_yet = 1; +#define XSTR(s) STR(s) +#define STR(s) #s + +volatile int with_checkpoint = 0; + int main () { alarm (300); + if (with_checkpoint) + { + /* We open a file and move file pos from 0 to 1. We set the checkpoint + when pos is 0, and restart it when pos is 1. This makes sure that + restarting the checkpoint excercises calling lseek in the + inferior. */ + + /* Open a file. */ + const char *filename = XSTR (BINFILE); + FILE *fp = fopen (filename, "r"); + + volatile int checkpoint_here = 0; /* Checkpoint here. */ + + if (fp != NULL) + { + /* Move file pos from 0 to 1. */ + int res = fseek (fp, 1, SEEK_SET); + assert (res == 0); + } + } + /* Spin until GDB releases us. */ while (dont_exit_just_yet) usleep (100000); diff --git a/gdb/testsuite/gdb.base/kill-during-detach.exp b/gdb/testsuite/gdb.base/kill-during-detach.exp index 26028d5fc34..a5b0127f4b7 100644 --- a/gdb/testsuite/gdb.base/kill-during-detach.exp +++ b/gdb/testsuite/gdb.base/kill-during-detach.exp @@ -39,10 +39,16 @@ if { [istarget "*-*-linux*"] && [target_info gdb_protocol] == ""} { set has_checkpoint false } -if {[build_executable "failed to prepare" $testfile $srcfile] == -1} { +set flags {} +lappend flags debug +lappend flags additional_flags=-DBINFILE=$binfile + +if {[build_executable "failed to prepare" $testfile $srcfile $flags] == -1} { return -1 } +set checkpoint_line [gdb_get_line_number "Checkpoint here"] + # Start an inferior, which blocks in a spin loop. Setup a Python # function that performs an action based on EXIT_P that will cause the # inferior to exit, and then, within the same Python function, ask GDB @@ -78,6 +84,14 @@ proc run_test { exit_p checkpoint_p } { } if { $checkpoint_p } { + # Active checkpoint-specific code in $srcfile. + gdb_test_no_output "set var with_checkpoint=1" + + # Run to line where we want to set the checkpoint. + gdb_breakpoint "$::srcfile:$::checkpoint_line" + gdb_continue_to_breakpoint "checkpoint line" + + # Set the checkpoint. gdb_test "checkpoint" \ "checkpoint 1: fork returned pid $::decimal\\." }