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Tue, 26 Oct 2021 08:10:18 -0700 (PDT) Subject: Re: [RFC 0/2] tls: add macros for coroutine-safe TLS variables To: Stefan Hajnoczi , Warner Losh References: <20211025140716.166971-1-stefanha@redhat.com> <2ca9c094-61e6-54b8-89a8-6dad22514c96@linaro.org> From: Richard Henderson Message-ID: <85df7de0-cebb-efe9-d26b-f459a37a6621@linaro.org> Date: Tue, 26 Oct 2021 08:10:16 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.13.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Received-SPF: pass client-ip=2607:f8b0:4864:20::52d; envelope-from=richard.henderson@linaro.org; helo=mail-pg1-x52d.google.com X-Spam_score_int: -22 X-Spam_score: -2.3 X-Spam_bar: -- X-Spam_report: (-2.3 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, NICE_REPLY_A=-0.215, RCVD_IN_DNSWL_NONE=-0.0001, SPF_HELO_NONE=0.001, SPF_PASS=-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: fweimer@redhat.com, Kevin Wolf , Thomas Huth , "open list:Block layer core" , QEMU Developers , Fam Zheng , sguelton@redhat.com Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On 10/26/21 6:22 AM, Stefan Hajnoczi wrote: > If "safe" TLS variables are opt-in then we'll likely have obscure bugs > when code changes to access a TLS variable that was previously never > accessed from a coroutine. There is no compiler error and no way to > detect this. When it happens debugging it is painful. Co-routines are never used in user-only builds. r~