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Tue, 14 Jul 2026 07:17:01 -0700 (PDT) From: Aadeshveer Singh To: qemu-devel@nongnu.org Cc: peterx@redhat.com, farosas@suse.de, pbonzini@redhat.com, philmd@mailo.com, lvivier@redhat.com, ayoub@saferwall.com, pierrick.bouvier@oss.qualcomm.com, Aadeshveer Singh Subject: [PATCH v3 05/11] migration: Make qemu_get_buffer_at() thread-safe Date: Tue, 14 Jul 2026 19:45:41 +0530 Message-ID: <20260714141547.1268000-6-aadeshveer07@gmail.com> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260714141547.1268000-1-aadeshveer07@gmail.com> References: <20260714141547.1268000-1-aadeshveer07@gmail.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=lists1p.gnu.org; Received-SPF: pass client-ip=2607:f8b0:4864:20::52a; envelope-from=aadeshveer07@gmail.com; helo=mail-pg1-x52a.google.com X-Spam_score_int: -17 X-Spam_score: -1.8 X-Spam_bar: - X-Spam_report: (-1.8 / 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, FREEMAIL_ENVFROM_END_DIGIT=0.25, FREEMAIL_FROM=0.001, 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: 2.1.29 Precedence: list List-Id: qemu development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: qemu-devel-bounces+importer=patchew.org@nongnu.org X-ZohoMail-DKIM: pass (identity @gmail.com) X-ZM-MESSAGEID: 1784038650647158500 Content-Type: text/plain; charset="utf-8" Remove the internal QEMUFile error state modification from qemu_get_buffer_at(). This function is called by two functions, both of which already check for unexpected return values and handle their own error reporting. Removing this shared state modification makes qemu_get_buffer_at() strictly thread-safe for concurrent disk reads, serving as a preparatory change for the upcoming fast snapshot load feature. Removed local error by passing errp to improve on error handling, consequently also change caller to use error_prevent and not error_setg. Signed-off-by: Aadeshveer Singh Reviewed-by: Peter Xu --- migration/qemu-file.c | 9 +++------ migration/qemu-file.h | 4 ++-- migration/ram.c | 6 +++--- 3 files changed, 8 insertions(+), 11 deletions(-) diff --git a/migration/qemu-file.c b/migration/qemu-file.c index d5a48115bd..0c28c878a9 100644 --- a/migration/qemu-file.c +++ b/migration/qemu-file.c @@ -550,17 +550,14 @@ void qemu_put_buffer_at(QEMUFile *f, const uint8_t *b= uf, size_t buflen, } =20 =20 -size_t qemu_get_buffer_at(QEMUFile *f, uint8_t *buf, size_t buflen, - off_t pos) +size_t qemu_get_buffer_at(QEMUFile *f, uint8_t *buf, size_t buflen, off_t = pos, + Error **errp) { - Error *err =3D NULL; - if (f->last_error) { return 0; } =20 - if (qio_channel_pread_all(f->ioc, buf, buflen, pos, &err) < 0) { - qemu_file_set_error_obj(f, -EIO, err); + if (qio_channel_pread_all(f->ioc, buf, buflen, pos, errp) < 0) { return 0; } =20 diff --git a/migration/qemu-file.h b/migration/qemu-file.h index 8f824c124d..966766788d 100644 --- a/migration/qemu-file.h +++ b/migration/qemu-file.h @@ -76,8 +76,8 @@ void qemu_set_offset(QEMUFile *f, off_t off, int whence); off_t qemu_get_offset(QEMUFile *f); void qemu_put_buffer_at(QEMUFile *f, const uint8_t *buf, size_t buflen, off_t pos); -size_t qemu_get_buffer_at(QEMUFile *f, uint8_t *buf, size_t buflen, - off_t pos); +size_t qemu_get_buffer_at(QEMUFile *f, uint8_t *buf, size_t buflen, off_t = pos, + Error **errp); =20 QIOChannel *qemu_file_get_ioc(QEMUFile *file); int qemu_file_put_fd(QEMUFile *f, int fd); diff --git a/migration/ram.c b/migration/ram.c index 4728f14d73..967db7c0db 100644 --- a/migration/ram.c +++ b/migration/ram.c @@ -4127,7 +4127,7 @@ static bool read_ramblock_mapped_ram(QEMUFile *f, RAM= Block *block, block->pages_offset + offset= ); } else { read =3D qemu_get_buffer_at(f, host, size, - block->pages_offset + offset); + block->pages_offset + offset, er= rp); } =20 if (!read) { @@ -4196,8 +4196,8 @@ static void parse_ramblock_mapped_ram(QEMUFile *f, RA= MBlock *block, bitmap_size =3D BITS_TO_LONGS(num_pages) * sizeof(unsigned long); =20 if (qemu_get_buffer_at(f, (uint8_t *)block->file_bmap, bitmap_size, - header.bitmap_offset) !=3D bitmap_size) { - error_setg(errp, "Error reading dirty bitmap"); + header.bitmap_offset, errp) !=3D bitmap_size) { + error_prepend(errp, "Error reading dirty bitmap"); return; } =20 --=20 2.55.0