Re: 回复: Fix segfault while accessing half-initialized hash table in pgstat_shmem.c

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From: Michael Paquier
Sent: Thursday, September 04, 2025 14:30
To: Steven Niu
Cc: Mikhail Kot; pgsql-hackers@lists.postgresql.org; to@myrrc.dev
Subject: Re: 回复: Fix segfault while accessing half-initialized hash table in pgstat_shmem.c

On Thu, Sep 04, 2025 at 02:31:34AM +0000, Steven Niu wrote:
> If pgstat_init_entry() errors on OOM, what would it returns to shheader, NULL?
> That would bring trouble to dshash_delete_entry().

Based on the proposal of patch 0002, the code would throw an error
after cleaning up the shared memory state.  The generation and
refcount number assigned inside pgstat_init_entry() would not matter
as well because the entry created by dshash_find_or_insert() would be
entirely gone.  So I am not sure what's the point you are trying to
make here.
--
Michael


Sorry, I made a mistake. I should say:
"If pgstat_init_entry() errors on OOM, the local variable shheader may be NULL. This would bring trouble to
pgstat_acquire_entry_ref()in the line 30 of patch 002".