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[50.253.99.174]) by smtp.gmail.com with ESMTPSA id a17sm8062827ios.36.2021.08.07.14.43.37 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 07 Aug 2021 14:43:37 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bsdimp-com.20150623.gappssmtp.com; s=20150623; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=vOkvP8eW9FaZE+oQEicIqxiTibF7uC5PjljIsjV9a8M=; b=pt7nvL/ZCuALCKXK9QCWkULpi8bP2R1yY6mbnJ86xJcIp+TM8DWJqnKHE9Wxeg6+RB LzoCw9IcbROaNTgXtFmFixG4OZObypc9USuDOsIqQZL4yctxGlCyN/98IrWaOp5+sHg/ mQ6RNKwC4iKOItVfpSAJtkJKHfhkGbn2Nye6+IRKConI0RiLcdPa7cE3s3EicwU9BsOr v4dmzx2roU69snDlSowdGTVXnqPiorHnHbdqb9hIuUTThcYlMHb68UCR1FiV0CQmd+08 cGfKOyHmC5tqCGv5CfkvY2F6P/hPhvNOVaPD4/GKQNXqJFqM2CnUMV1M5XhFrPVkDwTi hcKQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=vOkvP8eW9FaZE+oQEicIqxiTibF7uC5PjljIsjV9a8M=; b=XMeBV6qX63VEj+a+i7mrJGj7s2tRUaSd48XxNGeWk2gG8PadhkPMhwfqZ9EDexagYk Cq++SaQQ4s7ShzIzdrI7Pb6iHd6aSPcigx4bn9EBvVSPjC0ogdZEFzhj+sunLK7CynFq 5eexiovxF165x8qGDBQp3qSUSEwhVQNNI5JamtA853o6XFA7aeVjV1NivX9cypqxCPpa +9O6uF0VWPLctviLcB+W2qBqj88FOUm7wlSTjqdbESyoumlPPqVF1/PjbhqEYnQ7SQK3 1Bw3TuL1ptODHzd8COrQOLILXrn+feHPelbE+Imfdx2sANdN38PiEHUgGwE10DEcJK2k jfVA== X-Gm-Message-State: AOAM532YfPTXlXEio79a9gqId54gig7lNpKipRoRRhI11pPn8oYVZR0t +3Qe3F9LV5Py01y6V/0u+87Eb3/oD1Z/BXQG X-Google-Smtp-Source: ABdhPJyLS0HAPdm3PRC9VMokH1qbPaBdW2FiNXAg7BPjmkQsz6NcnN3w4QGLhJTjuqCaJL0Zp63Guw== X-Received: by 2002:a05:6e02:1aa3:: with SMTP id l3mr23292ilv.299.1628372618046; Sat, 07 Aug 2021 14:43:38 -0700 (PDT) From: Warner Losh To: qemu-devel@nongnu.org Subject: [PATCH for 6.2 47/49] bsd-user: Implement interlock for atomic operations Date: Sat, 7 Aug 2021 15:42:40 -0600 Message-Id: <20210807214242.82385-48-imp@bsdimp.com> X-Mailer: git-send-email 2.32.0 In-Reply-To: <20210807214242.82385-1-imp@bsdimp.com> References: <20210807214242.82385-1-imp@bsdimp.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Received-SPF: pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) client-ip=209.51.188.17; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists.gnu.org; Received-SPF: none client-ip=2607:f8b0:4864:20::d36; envelope-from=imp@bsdimp.com; helo=mail-io1-xd36.google.com X-Spam_score_int: -18 X-Spam_score: -1.9 X-Spam_bar: - X-Spam_report: (-1.9 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, SPF_HELO_NONE=0.001, SPF_NONE=0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: kevans@freebsd.org, Warner Losh , Warner Losh , Stacey Son Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: "Qemu-devel" X-ZohoMail-DKIM: fail (Header signature does not verify) X-ZM-MESSAGEID: 1628373367470100001 Content-Type: text/plain; charset="utf-8" From: Warner Losh Implement the internlock in fork_start() and fork_end() to properly cope with atomic operations and to safely keep state for parent and child processes. Signed-off-by: Stacey Son Signed-off-by: Warner Losh Reviewed-by: Richard Henderson --- bsd-user/main.c | 23 +++++++++++++++++++++++ 1 file changed, 23 insertions(+) diff --git a/bsd-user/main.c b/bsd-user/main.c index 7ba616a995..2b0716d245 100644 --- a/bsd-user/main.c +++ b/bsd-user/main.c @@ -85,15 +85,38 @@ unsigned long target_dflssiz =3D TARGET_DFLSSIZ; /* i= nitial data size limit */ unsigned long target_maxssiz =3D TARGET_MAXSSIZ; /* max stack size */ unsigned long target_sgrowsiz =3D TARGET_SGROWSIZ; /* amount to grow stack= */ =20 +/* Helper routines for implementing atomic operations. */ =20 void fork_start(void) { + start_exclusive(); + cpu_list_lock(); + mmap_fork_start(); } =20 void fork_end(int child) { if (child) { + CPUState *cpu, *next_cpu; + /* + * Child processes created by fork() only have a single thread. + * Discard information about the parent threads. + */ + CPU_FOREACH_SAFE(cpu, next_cpu) { + if (cpu !=3D thread_cpu) { + QTAILQ_REMOVE_RCU(&cpus, cpu, node); + } + } + mmap_fork_end(child); + /* qemu_init_cpu_list() takes care of reinitializing the + * exclusive state, so we don't need to end_exclusive() here. + */ + qemu_init_cpu_list(); gdbserver_fork(thread_cpu); + } else { + mmap_fork_end(child); + cpu_list_unlock(); + end_exclusive(); } } =20 --=20 2.32.0